Researchers have determined supplementing horses’ diets with protein within a short but safe timeframe after exercise might help them build muscle mass more than providing the same supplement at regular mealtimes.

A high-protein snack—given as soon as the horse is resting again—could add critical amino acids to the bloodstream when muscles need them for repair and damage control, said Patty Graham-Thiers, PhD, professor and department head of the equine studies program at Emory & Henry University, in Virginia.

In a previous study Graham-Thiers and her colleagues found that supplementing young and even senior horses’ diets with amino acids helped improved their muscle mass—which horses naturally lose with advancing age. It made her wonder whether the supplements might be even more useful if they’re provided right when the body needs them most, shortly after exercise.

“In humans it’s common to consume protein post-exercise to help with muscle mass recovery and development, especially in body builders,” she said. “So, I thought, what if amino acids are delivered (to horses) after exercise when the body is recovering and needs amino acids, either for repair or development of muscle tissue?”

Feeding Horses a High-Protein Supplement After Exercise

To find out, Graham-Thiers and Kristen Bowen, BA, an equine exercise and nutrition research assistant at Emory & Henry, tested the effects of supplementation timing on eight healthy adult riding school horses. The horses participated in light to moderate maintenance exercise one to two hours per day, five days per week for 12 weeks.

Caregivers provided all the horses morning and evening meals consisting of grass hay, textured feed, and corn. In addition, the animals consumed a daily high-protein pellet made of 32% crude protein.

Half the horses received the protein supplement split into their two daily meals, while the other half received the supplement about 20 minutes after exercise—once their heart rates, breathing, and body temperatures dropped to regular resting levels. On rest days without exercise, these four horses ate their protein pellets as a separate midday snack.

The team collected urine and feces from each horse for four days before and after the 12-week experiment. They also took blood samples at the start and end of the study period, which they drew immediately after exercise and one and three hours later.

Studying the Effects of Feeding Timing on Muscle Health

The researchers used the urine and fecal samples to calculate nitrogen balance. Blood plasma samples allowed them to measure amino acid concentrations, albumin, plasma urea N (PUN), creatine kinase (CK), and creatinine.

The results of these tests revealed horses receiving supplementation in their meals had higher plasma concentrations of amino acids than those receiving the supplement shortly after exercise. The researchers explained this is likely because the horses had consumed more protein before exercise than the others, which had not yet had their daily protein pellets.  

The horses receiving the supplement after exercise had rising amino acid concentrations at the one-hour and three-hour post-exercise readings—likely reflecting a beneficial amino acid pool, the team said. The other horses’ amino acid concentrations, meanwhile, dropped.

Additionally, horses receiving the supplement just after exercise retained nitrogen better, which suggests they might have a timelier supply of proteins and amino acids for muscle protein repair and development.

The post-exercise supplementation group also had higher creatinine levels (a known marker of muscle mass) in their plasma. And they had less creatine kinase—an indicator of muscle protein damage or breakdown. This suggests horses might have been recovering faster after exercise than the other group, the researchers said.

Combined, the findings suggest feeding horses a high-protein meal shortly after exercise could help boost levels of circulating amino acids, which could aid muscle protein development while protecting against muscle protein breakdown.Even so, Graham-Thiers said more research is necessary before she and her colleagues can offer concrete supplementation guidelines.

Take-Home Message

“Ideally, I would suggest providing a small high-protein meal when it is safe to do so after exercise,” she noted. “However, this is not always practical. I would encourage riders to be aware of the time frame between feeding and exercise; the longer that time has been, the more important it might be for recovery to offer a small high-protein meal after exercise.”

The study, ”Timing of feeding a protein supplement on nitrogen balance and plasma amino acids during exercise recovery in horses,” appeared in the Journal of Animal Physiology and Animal Nutrition in July 2024.

Q. I am an avid event rider and enjoyed watching the Defender Kentucky Three-Day Event. What kinds of nutritional support can you give horses competing in this level of competition to help them recover?

A. This is a great question. Any post-competition recovery effort starts with the base diet, which meet the horse’s daily requirements leading up to the competition. No long-term deficiency is going to get fixed in the short period during competition, so a balanced diet appropriate for the horse’s discipline and work level is crucial.

Part of that is ensuring the horse is getting the right kind of fuel to support the type of work that he’s asked to do. Event horses won’t only be utilizing stored carbohydrate on cross-country day but hopefully their reserves of fat stores, as well. Cross-country efforts will deplete glycogen stores (stored carbohydrates) in the horse’s muscles. The horse will need glycogen again for the show jumping phase, so restoring those stores is an important component of recovery.

Horses don’t restore muscle glycogen after heavy work particularly quickly, however—it can take up to 72 hours to fully replenish this important fuel source. The tactics human athletes use—such as “carb loading”—don’t work particularly well in horses. Not only has research found carb loading horses relatively ineffective at increasing muscle glycogen, loading with carbs such as starch could lead to colic.

Hydration

One thing that does help improve glycogen replenishment is making sure the horse is adequately hydrated. Muscle glycogen requires water for storage, so a dehydrated horse is less able to generate new muscle glycogen stores.

Hydration measures should begin well before cross-county day. Many horse travel long distances to events, and these long journeys cause surprisingly large amounts of sweat loss. Even when you can’t see the sweat, horses can lose very high levels of electrolytes during transportation. This puts them at a disadvantage before the competition even starts. Feeding salt every day and adding a well-formulated electrolyte while traveling will help horses remain hydrated. Consider arriving a day early if travel is particularly long, so your horse has time to fully rehydrate and recover from the journey before competition starts.

Horses that drink saline solution after exercise have been shown to consume more water in the subsequent hours than those that drink plain water. Consider acclimating your horse to drinking water after work with either salt or electrolytes so this is a normal practice at events.

Muscle Recovery

Hard-working horses might be muscle-sore after cross-country, and supporting recovering muscle might help your horse come out on Day Three with a little more spring in his step. Vitamin E is an extremely important antioxidant for muscle health. Oxidation of glycogen and fats to create energy for muscle contraction causes the formation of free radicals. These oxidizing compounds are unstable and damage cell walls if not removed. Vitamin E helps stabilize them by donating an electron so that a cascade of free radical damage is prevented.

Horses need to get adequate vitamin E every day and, because of individual variation, some horses—even when receiving enough vitamin E to meet the National Research Council guidelines—are vitamin E-deficient. The best way to know your horse is getting enough vitamin E is to ensure his base diet is meeting the stated requirement. Then have your veterinarian test his serum vitamin E levels. This will tell you whether you need to supplement additional vitamin E daily. Providing extra natural vitamin E after particularly heavy work such as cross-country day might aid in recovery.

During recovery from exercise, muscle protein synthesis increases in order to repair muscle tissue damaged during work. If adequate dietary amino acids are available in the 24 to 48 hours post work, a net protein gain might occur. The most important amino acid for this process is leucine, which is a branched chain amino acid (BCAA). For this reason, administering a supplement that provides BCAAs after especially heavy exercise might help shorten recovery.

Take-Home Message

In general, after strenuous exercise, ensure your horse has access to good-quality forage (this is a safe way to replenish carbohydrates and encourages water intake), increase electrolyte intake to replace losses and encourage water consumption, ensure adequate natural vitamin E, and provide BCAAs. Incorporating these into your program will help your horse be at his best for the third day as well as recover from the overall event as quickly as possible.

Understanding the important role electrolytes play in healthy performance horses

Electrolytes are minerals that break up into electrically charged ions in water. They play crucial roles in the functions of all cells and are particularly important for muscle and nerve function and fluid balance within the horse’s body. When horses sweat, they lose a significant amount of electrolytes from their body. These must be replaced for the horse to maintain optimal fluid balance, nerve function, and muscle function.

Manufacturers market a plethora of electrolyte products in a variety of forms to horse owners. Understanding when, how much, and which products to supplement is critical for optimizing equine health and performance.

Another Kind of Sweat Equity

When your horse sweats, you might see a white residue that remains on his hair coat after the sweat evaporates. Those are the residual electrolytes lost through sweat. Therefore, even by simply looking at a working horse it becomes obvious that the more he sweats, the more electrolytes he has lost. The primary electrolytes a horse loses in sweat are sodium, chloride, and potassium. He also loses calcium, magnesium, phosphorus, and sulfur, but in smaller quantities.

Don Kapper, a professional animal scientist based in Beach City, Ohio, with more than 37 years of experience formulating products, researching, and teaching in the industry, says, “Electrolytes are anions and cations (negatively and positively charged ions, respectively), so the positives and negatives must work together. When the horse runs out of cation or anion molecules the muscle will stop functioning properly. Therefore, when electrolytes are supplemented, the anions and cations must be balanced and match what the horse has lost in their sweat.”

Why Do Horses Need Supplemental Electrolytes?

Electrolytes tend to be front of horse owners’ minds in the summer months but, regardless of season, if a horse sweats, he should consume supplemental electrolytes. Sweating is the primary method of thermoregulation for working horses. Therefore, when temperatures increase, electrolyte losses are more substantial. Michael Lindinger, PhD, a former professor at the University of Guelph, in Ontario, Canada, and current president of the Nutraceutical Alliance, also in Ontario, notes, “When horses sweat, they are losing a lot of electrolytes through their skin, nearly three times more than humans. Therefore, if the horse is sweating even for just one hour, they can lose a significant amount and may become dehydrated.”

The electrolyte levels your horse needs are directly proportional to what he loses in sweat. In order to decipher how much you should be supplementing, rely on the National Weather Service’s heat index chart (weather.gov/ffc/hichart). This chart takes into consideration the day’s temperature, humidity, and work intensity level. Due to horse sweat being more concentrated with electrolytes than human sweat, it is imperative we provide electrolytes to dehydrated horses and don’t just give them water.

When a dehydrated horse receives plain water but cannot replenish electrolytes, it can negatively affect his ability to recover. “A key role of electrolytes is that they retain fluid in the body, both within cells (intracellularly) and outside of cells (extracellularly). Therefore, the only way to rehydrate a dehydrated horse is to restore hydration with a solution of water and electrolytes,” says Lindinger.

The Benefits of Supplementing Electrolytes

Lindinger, in a study published in the Journal of Experimental Physiology, demonstrated that providing a properly formulated oral performance electrolyte administered in solution at the recommended rate can delay the onset of fatigue by over 22%, reduce muscle cramping, and improve the horse’s ability to recover and perform the following day.

Kapper notes, “During this research, the electrolyte was detected in the bloodstream within 10 minutes of administration, and within 10 minutes of starting to exercise was present in the sweat.” To do this, the optimal osmolarity (concentration) of the performance electrolyte solution must be attained. The amount of electrolyte powder Lindinger and his team used was 4 ounces/gallon of water.

Indeed, to capture the benefits of electrolyte supplementation described, it is not always enough to simply provide salt and water to your horse.

Our sources don’t consider many commercially available electrolyte products properly formulated as performance products. A performance electrolyte replenishes what the horse has lost in his sweat. So if the product does not match the losses, it might not be effective for hydrating the horse, delaying fatigue, or improving his ability to recover from work.

Performance Electrolytes

The chemical makeup of equine sweat expressed as an equation is Na + K + Ca + Mg = Cl + P + S. Again, “performance electrolytes are those that emulate what has been lost in sweat,” says Kapper. “The addition of dextrose also improves the rate of absorption in the small intestine. When you are choosing a performance electrolyte for your horse, the sodium and potassium should be close to equaling the amount of chloride in the product.” You can find this information in the guaranteed analysis of the product.

Understanding ideal formulation of performance electrolytes is critical to choosing the right product for your hard-working horse. For instance, Himalayan salt and sea salt are very popular among horse owners. “However, they are very different from the electrolyte composition of sweat and, therefore, poor choices when aiming to rehydrate a horse after working,” says Lindinger.

“Supplements containing greater than 70% salt (NaCl₄) are not performance electrolytes. They are simply expensive salt,” adds Kapper.

Therefore, when shopping for an optimal performance electrolyte product for your horse, read the guaranteed analysis and compare it to the equation of electrolytes in equine sweat. Nutritionists typically recommend using salt to meet your horse’s daily sodium and chloride requirement and then adding a performance electrolyte when he starts sweating.

Consequences of Dehydration and Electrolyte Imbalance

Dehydration has a variety of negative consequences ranging from fatigue and weakness to serious health issues such as colic and tying-up. Kapper says, “Most horse owners are familiar with the skin-tent test and looking at the color of the gums when assessing for dehydration. However 14 other parameters exist that horse owners can check. The Horse Health Check (tool), developed by Art King, DVM, and Gayle Ecker at the University of Guelph, details 16 checkpoints to evaluate dehydration.”

As mentioned earlier, when a horse has lost electrolytes in his sweat and becomes dehydrated, the body will stop working properly. “Nerves and muscles will stop functioning,” says Lindinger.

Kapper adds, “The positive and negative (electrolytes) must work together so, when there is an imbalance, the horse owner will notice muscle soreness starting, more stumbling, and a shortened stride.” When considering elite performance horses that compete multiple days in a row, delaying fatigue and muscle soreness can make a significant difference in their abilities to successfully perform.

Administering Electrolytes to Horses

When selecting from the myriad equine electrolyte products and administration methods available, horse owners must understand how the horse’s body absorbs electrolytes and how they contribute to rehydration.

“All electrolytes are hydroscopic and will dehydrate your horse if they do not drink enough water after administering,” explains Kapper. For this reason, adding the electrolytes into an appropriate volume of water for dehydrated horses is extremely critical.

Additionally, he does not recommend paste electrolytes for this reason. “All paste electrolytes will lie in the digestive tract of the horse until they draw enough water from the body to break them down,” he adds.

When mixing the solution, follow the manufacturer’s instructions. “Use concentrations that are more dilute if palatability is an issue,” says Lindinger.

One of the biggest challenges owners face when supplementing electrolytes in their horses is determining how much they should offer, and if top-dressing over feed is adequate or if they need it in solution. “Feeding electrolytes as a top dressing is common, however, this should not be done for a dehydrated horse,” says Lindinger.

Providing the electrolyte in solution is the gold standard, but for horses traveling, idle, or at lower levels, top dressing the performance electrolyte on feed at the recommended amount per day is often adequate. For horses at the upper levels and exercising intensely, the electrolyte solution should be provided during and after transport to events to ensure optimal hydration prior to training and competition sessions. In addition, electrolytes are best provided within 45 minutes after training or competing.

“Relying on the average heart rate of the training session can assist horse owners in determining how much electrolyte to give,” notes Kapper. “For example, a horse that is sweating for 15 minutes during a work session will not require the same electrolyte supplementation as an endurance horse doing 100 miles per day.”

Kapper’s charts summarize electrolyte supplementation recommendations in various situations.

Supplementation Recommendations for ‘MILD’ Heat Stress Index (Below go)

Supplementation Recommendations for ‘MODERATE’ Heat Stress Index (90-105)

Supplementation Recommendations for ‘SEVERE’ Heat Stress Index (Over 105)

Tips for Supplementing Finicky Horses

When introducing a performance electrolyte to your horse’s diet, start it at home—not at an event or during travel. “Buy a small amount of the performance electrolyte and try it, especially with finicky horses,” says Kapper. If you sometimes add it as a top dressing and other times mix the product into water, Kapper recommends using the same product both places to ensure taste consistency.

“When introducing a performance electrolyte mixed with the horse’s water, start with a dilute solution and, over the course of multiple days, slowly increase the concentration to full strength,” says Lindinger. If your horse does not like one product, do not hesitate to try a different one.

Including dextrose in performance electrolytes should improve palatability. Nutritionists know that when sugar content exceeds what the body needs, muscles will weaken but, as noted earlier, adding dextrose to performance electrolytes improves absorption. Some practitioners don’t recommend adding electrolytes to feed or water because of the risk of decreasing feed consumption and causing dehydration; instead, they recommend a free-choice electrolyte. What you offer depends on the horse.

Take-Home Message

When horses sweat, they lose a significant amount of electrolytes that must be replaced to help them maintain adequate fluid balance as well as muscle and nerve function. Dehydration can be detrimental to equine health and performance. Therefore, adopt effective electrolyte supplementation strategies to promote hydration. Remember to critically review the  guaranteed analysis prior to purchasing a performance electrolyte and introduce it to your horse to consume at home prior to traveling or competing in warmer weather.

In performance horses, every aspect of care—from nutrition and farriery to conditioning and recovery—works together to influence the animal’s long-term soundness and success. Veterinarians or equine nutritionists might recommend supplements as part of multimodal approach to support horses’ overall wellness or help manage chronic conditions. While they’re not intended to replace foundational veterinary care or good nutrition, supplements can complement a comprehensive management plan when thoughtfully selected and used in conjunction with targeted therapies and training programs.

“Supplements should only be used to augment a preexisting care plan,” says Nimet Browne, DVM, MPH, Dipl. ACVIM, of Hagyard Equine Medical Institute, in Lexington, Kentucky. “We need to understand that they are not going to solve all our problems, but they can bring out the best in our athletic partners.”

What Is a Multimodal Approach to Performance Horse Health?

A multimodal management strategy involves using multiple treatments or techniques, each targeting a different aspect of a problem (i.e., pain or inflammation). This could mean pairing a nonsteroidal anti-inflammatory drug (NSAID) with physical therapy or combining regenerative therapies with appropriate nutrition and supportive shoeing.

“By combining different modalities and agents, we hope to achieve a greater level of pain relief,” Browne says. “For example, we might use extracorporeal shock wave therapy in addition to NSAIDs to alleviate back pain.”

Because the FDA classifies only products that treat, cure, or prevent disease as drugs—requiring them to pass rigorous approval processes—most owners turn to supplements to complement the diet or fill nutritional gaps. Supplements have comparatively limited regulatory oversight, meaning owners, veterinarians, and nutritionists should thoroughly research a supplement before feeding it to a horse.

Supplements should never replace foundational management, such as proper conditioning and veterinary diagnostics. “If you’re relying on a supplement to resolve (for example) lameness, it’s very important that you first have a diagnosis so that you know what you are dealing with to know if that product might help,” says Emma Adam, DVM, PhD, Dipl. ACVIM, ACVS, assistant professor at the University of Kentucky’s Gluck Equine Research Center, in Lexington. “Supplements can complement a good program, but they are not a substitute for suboptimal training, nutrition, or management practices.”

How to Evaluate a Supplement for Horses

When choosing a supplement for a performance horse, veterinarians and owners should consider its quality, bioavailability, and clinical backing as the top priorities. “Start by consulting your veterinarian,” Browne says. “They can help identify ingredients and dosages that would help the particular problem you are trying to address.”

For example, she adds, “There are many formulations of vitamin E on the market, but many of them have poor absorption. Working with your veterinarian, you can choose the most appropriate formulation.”

Adam agrees and emphasizes the importance of evidence-based decision-making. “We can’t assume all supplements are the same,” Adam says. “I look for peer-reviewed studies or data that support a supplement’s claims. Products backed by research and developed by reputable companies demonstrate that company’s commitment to their product and to their customer.”

Bioavailability—the rate and extent to which the body can absorb and use an ingredient—can be a critical factor in a supplement’s effectiveness, says Adam. High-quality and verified ingredients, correct dosing, and a horse’s individual metabolism all affect outcomes. “If the supplement isn’t being absorbed, it doesn’t matter how promising it sounds,” she says.

Timing Performance Horse Supplement Administration

Timing of administration can influence a supplement’s efficacy. For example, owners should feed most supplements consistently to maintain steady therapeutic levels. Owners might need to give other supplements, such as those used for recovery or acute stress, around competition. “There are ingredients that help maintain athletic ability and support recovery after a tough workout,” Browne says. “These tend to have a short duration of action and therefore need to be administered closer to competition time.”

Common Equine Supplement Mistakes to Avoid

Horse owners often make the mistake of over supplementing—adding multiple products without a clear plan or awareness of potential ingredient overlaps, says Browne. “Although often not dangerous, doubling up on ingredients can lead to increased expenses and complicate feeding routines,” she says. “It can also make horses reluctant to eat or resistant to oral medications.”

However, in some cases, over supplementing might be risky because little research available to demonstrate how multiple supplements fed together can affect horses, says Adam. “Owners want to do the best for their horses and may be tempted to add product after product, but without guidance and data that strategy is inefficient at best and risky at worst.”

Choosing Equine Supplements as a Team Effort

Ultimately, effective supplement use requires collaboration between veterinarians, farriers, trainers, and owners. This includes being aware of the legal and ethical considerations around supplement use, especially in competition settings.

“It is extremely important that both veterinarians and professionals have a solid understanding of the rules and regulations set forth by the governing body of their sport,” Browne says. “These rules are in place to ensure the health and safety of the equine and human athlete.”

Adam encourages open communication between all involved in a horse’s care. “When everyone’s on the same page, the horse benefits,” she says. “Transparency helps prevent negative interactions and ensures the overall plan is coherent.”

Take-Home Message

When addressing a specific problem in a performance horse, supplements can be one part of the solution and work best when integrated into a larger strategy. Veterinarians, owners, farriers, and nutritionists should work together to create a multimodal management plan for performance horses built on transparency and including high-quality nutrition, routine veterinary care, medical management, and complementary therapies.

“Supplements can be one piece of a comprehensive care plan,” says Adam. “It’s about doing what’s right for each horse, backed by science, experience, and teamwork. Where possible use evidence-based practices rather than anecdotal experience. Always tailor choices to the individual horse’s needs and medical history.”

Enteroliths are a type of foreign body that can be found in horses’ intestines and are one possible cause of colic, or abdominal pain. Unlike sand or gravel, which horses ingest when they are grazing or eating outside, enteroliths develop when mineral deposits form in concentric layers around a central nidus, such as a piece of wire, small stone, twine, etc., in the large colon (the stretch of intestine between the cecum and the transverse colon). Horses can either have one enterolith (usually round and large) or multiple (often tetrahedral in shape, meaning they have angles or corners).

What Causes Enteroliths?

The cause behind enteroliths—and, especially, why some horses develop them but not others—is still not fully understood. Feeding high levels of alfalfa hay, particularly in California or other locations out west, has been associated with enterolith formation. Decreased turnout and limited access to pasture also have been linked to their development, possibly because of decreased intestinal motility or increased ingestion of alfalfa when stalled. Certain horse breeds (Arabians, Morgan horses, American Miniature horses, and Saddlebreds) have been shown to be more at risk for forming enteroliths.

Enteroliths cause problems when they get large enough that they begin to pass into the transverse or small colon. The diameter of the transverse and small colon is much smaller than the adjacent large colon, so the enteroliths become wedged. Once wedged they block food and gas from traveling out of the intestine, causing abdominal pain and signs of colic.

Some horses with enteroliths could have a history of recurrent colic (repeated colic episodes) due to enteroliths intermittently blocking the intestine and then other times allowing food and gas to pass normally. When the enterolith becomes completely wedged the horse will show signs of severe colic due to gas distension. If the enterolith is large enough and puts pressure on the intestine, it can cause necrosis of the intestinal wall in that area and lead to leakage of feces into the abdomen and secondary infection. In these cases horses show lethargy, decreased appetite, and fever, eventually progressing to signs of sepsis (a life-threatening systemic inflammatory response to infection) and shock. Due to how firmly enteroliths become lodged in the intestines, the treatment for enteroliths is always surgery.

Diagnosis

Veterinarians usually diagnose enteroliths at the time of colic surgery, when the colic signs do not respond to medical treatment, and/or the horse’s colon becomes distended with gas due to blockage by the enterolith. Abdominal X rays can be performed, but in most cases enteroliths are hidden by the large amount of tissue in the horse’s abdomen, making them difficult to detect.

Prevention

If your horse has had enteroliths before, veterinarians recommend taking preventive measures, because there is some evidence they can form again. In these cases, avoid feeding alfalfa and provide as much turnout on pasture as possible.

If at any point you see what looks like an enterolith in your horse’s manure, tell your veterinarian, because the presence of one enterolith (especially if it has a tetrahedral shape) often means there are more in your horse’s intestines. And if your horse shows signs of colic, you should always contact your veterinarian immediately.

Q. How long does it take for pasture grass sugar levels to drop after the sun goes down?

—Debra, Texas

A. The level of sugar in pasture grass varies due to several factors, including the weather, how stressed the grass is, its maturity, the time of year, and the time of day. As sun shines on pasture grass, the plants photosynthesize. This creates sugar stores the plan uses overnight to keep growing. Therefore, grasses tend to have higher sugar contents later in the day compared to earlier in the day.

Time Pasture Access Carefully

Generally, veterinarians and nutritionists recommend horses sensitive to sugar in pasture grass (such as those with insulin resistance, equine metabolic syndrome, or a history of laminitis) graze very early in the morning. It takes several hours after the sun sets for sugar levels to drop, so ideally try to avoid grazing before 3 a.m. And, because sugar levels start to build up again with sun exposure, it’s best to remove sensitive horses from pasture by about 10 a.m. If there’s significant cloud cover, you might be able to leave horses out a little longer, because photosynthesis (which relies on the sun) will be slower and therefore the amount of sugar will be lower.

One exception would be if the temperature drops below about 40°F overnight. At this temperature and below, the plants’ growth rate slow, which means stored sugars aren’t used up. As such, they’ll still be high in the early morning. In this situation, potentially at-risk horses should not have pasture access.

And, you must consider that some very sensitive horses might never be able to graze safely, while others can with careful grazing and pasture management. It all depends on the individual horse. Grazing muzzles are a very useful tool to help limit grass intake but still allow pasture access. Studies have shown that some muzzles can limit intake by as much as 80%.

Proper Pasture Management

Another important consideration is that most of the sugar in grasses tends to be in the bottom 3 to 4 inches of the plants. While it might be tempting to think that a very short, overgrazed pasture is safe because there’s “nothing out there,” such pastures present several risks—grasses are very stressed and only the lower inches of the plant are available, meaning these pastures can be very high in sugar.

As such, proper pasture management is very important to keep grasses from becoming stressed. This means horse owners need to properly fertilize and irrigate (if necessary) pastures.

It’s better for the plant and safer for the horse to stop grazing when the pasture has only about 3 to 4 inches of height left. This not only reduces sugar intake by your horse but also leaves some leaf for the plant so that it can regrow without having to dip in to root stores too heavily.

Take-Home Message

With an understanding of pasture grass metabolism and careful pasture and grazing management, many horses should be able to safely graze for at least part of the day. But, always consult your veterinarian or equine nutritionist before turning out your potentially sugar-sensitive horses on pasture.

With thousands of equine supplements on the market—ranging from joint support and digestive aids to calming formulas and coat enhancers—horse owners often look to veterinarians for guidance on what their animals might need. Veterinarians can help them determine when supplements are necessary for their horses, which ones are appropriate, and how to avoid ineffective or potentially harmful choices.

Start With the Forage

Carey Williams, PhD, equine extension specialist and professor at Rutgers University, in New Brunswick, New Jersey, says supplement discussions should always begin with the horse’s core diet in mind.

Forage should be the foundation, Williams says, followed by a concentrate or other commercial feed appropriate for the horse’s age, workload, and physiological status. For example, a broodmare or growing horse needs a different feed than a performance or pleasure horse. “Then you can decide—is there (a specific concern) that a supplement might help with?” she says.

If the diet is already balanced and the horse has no underlying issues, Williams says supplements might not be necessary at all.

Making Informed Equine Supplement Decisions

Once they’ve identified a need, veterinarians can help clients evaluate product options by focusing on transparency and research. “Some companies won’t be doing their own research, but they might cite published studies on ingredients in their product,” Williams says.

Veterinarians should direct owners to supplements with labels that include detailed ingredient lists, recommended dosages, and explanations of function. Vague phrases such as “proprietary blend” can be red flags. “The more specifics a company provides, the more confident I am in their product,” she says.

She also advises veterinarians to recommend ingredients rather than specific brands if they do not have a brand with which they are comfortable. “If you’re not familiar with a company, suggest functional ingredients like omega-3s from a particular source or specific antioxidants,” says Williams. “That way, the owner can do some research on their own or consult a nutritionist.”

Evaluating Equine Supplement Quality and Avoiding Risk

Quality control ranks among the most important factors to consider when choosing a supplement for your horse. Veterinarians can help clients look for companies that publish their testing protocols or quality assurance processes on their websites. “Reputable companies will show how they test their products, what methods they use, and how they ensure consistency,” Williams says.

She adds that cost can be a helpful indicator, though not a guarantee, of quality. “You do often get what you pay for,” she explains. “If a supplement is dramatically cheaper than others with similar ingredients, it should prompt questions. Is it underdosed? Has it been sitting on a shelf for years? Is the company cutting corners?”

She finds low-cost supplements from companies with limited public information or no customer support especially concerning. “Reputable companies are happy to discuss their product with you, including safety testing and research on it,” she says. “They spend a lot of money doing this, so they want everyone to know.”

Navigating Client Conversations About Equine Supplements

When a supplement serves no clear benefit or risks interfering with veterinary treatment, communication becomes essential. Williams often works alongside veterinarians during consultations to evaluate horses’ full diets and provide evidence-based recommendations.

“In cases where the vet suspects a supplement is doing more harm than good, we’ll go over the label with the client together,” she says. “Sometimes it’s not about the brand, but about the dose being too low to be effective, the supplement interacting with a medication, or they are feeding several products with overlapping ingredients.”

To help owners feel comfortable making changes to their horses’ supplement regimens, Williams recommends gradual adjustments. “I always suggest decreasing the dose first,” she says. “If they see no change, they’re usually more open to discontinuing it. It’s a good way to determine if the supplement is having an effect or not.”

Working With Equine Nutrition Professionals

Not all veterinarians are confident advising their clients about equine nutrition, which is where collaboration with a nutritionist can be helpful. Williams encourages veterinarians to contact equine extension specialists at their states’ land-grant universities, many of whom offer free or low-cost consulting.

“If a vet isn’t confident evaluating a ration, they can call someone like me,” she says. “Every state has cooperative extension, and we also have a national network. If I get a call from another state, I can help them out myself if their field is not nutrition, or I can refer them to a trusted colleague who can.”

Understanding Equine Supplement Regulation Gaps

Unlike prescription medications, equine supplements are not subject to FDA regulation, and manufacturers do not need to demonstrate efficacy before products reach the market. Veterinarians should communicate this to clients so they understand the importance of thoroughly researching supplements before purchasing them, says Williams. “That’s why it’s so important to stick with companies that are transparent, publish their ingredient lists, and explain their quality control processes,” she adds.

Williams also recommends that clients call companies directly to ask questions. “A reputable company should be able to explain what’s in their product and why,” she says. “If they avoid your questions or don’t respond at all, that’s a problem.”

Take-Home Message

Veterinarians can help clients make responsible, informed decisions about nutritional supplements for their horses. By evaluating the base diet, recommending evidence-based ingredients, and collaborating with qualified nutritionists, they can provide practical guidance grounded in science.

“There are good supplements out there,” Williams says. “But they should be used intentionally and with a clear purpose. It’s about solving a problem—not just adding something extra because they read about it online.”

This article was originally published in the April 2020 issue of The Horse. 

Equine nutritional supplements have become so popular that many owners view them as staples rather than simple additives. Further, manufacturers have designed and marketed these supplements so successfully that horses often receive several products per day to manage various conditions. For example, one study reported that certain populations of competitive horses receive about four nutritional supplements a day (Williams CA et al., 2012).

Offering multiple nutritional supplements can have a number of outcomes, not all of which are beneficial:

1. Your horse flourishes at the hands of supplementation, benefiting from targeted nutrition strategies.

This is an ideal situation. Having your veterinarians evaluate your horse’s physical condition frequently and reviewing his diet will help achieve the maximal response to any supplementation regime.

2. An oversupplemented horse receives an excess of certain nutrients.

While this approach might address several health issues simultaneously, nutritional supplements are expensive, making offering excessive nutrients uneconomical. Further, dietary imbalances might develop secondary to oversupplementation that can potentially result in deleterious nutrient interactions. A classic example of this is vitamin E—a popular nutritional supplement. High levels of vitamin E can lower systemic beta-carotene levels, which can potentially result in a vitamin A deficiency. Further, excess nutrients excreted in urine and feces negatively affect the environment.

3. You don’t see any response.

In this case you must take a step back and critically assess the situation. Is your horse not responding because the diagnosis is incorrect and you are supplementing the wrong product? Or is the product you are offering not up to snuff? In other words, does your selected supplement actually contain the type and amount of ingredient listed on the product label? Because the U.S. Food and Drug Administration (FDA) doesn’t regulate nutritional supplements, poor-quality supplements can surreptitiously infiltrate the market.

When choosing a quality supplement, follow the SMART supplementation strategies:

S—Shop Around. Do your research to identify a quality product most likely to contain the type and amount of active ingredient the label claims. When comparing products, use the ACCLAIM system:

• A name you recognize? Do you recognize the manufacturer? Look for products manufactured by established companies that provide educational materials for veterinarians and consumers.
• Clinical experience. Companies that support clinical research and test their products for safety, efficacy, and bioavailability with results published in peer-reviewed journals are more likely to have quality products.
• Contents. The product label should include all active and inactive ingredients/fillers.
• Label claims. Supplements with realistic label claims based on scientific study results, rather than testimonials, are preferable. Avoid products with illegal claims to diagnose, treat, cure, or prevent a disease.
• Administration recommendations. Look for products with clear administration recommendations with the recommended dosages based on published clinical trials.
• Ingredients. Products with some form of pre- and/or post-market surveillance in place and companies that have voluntarily instituted current Good Manufacturing Practices (cGMPs) and other quality-control and -assurance techniques are more likely to be reputable.
• Manufacturer information. This should be clearly stated on the label, preferably in concert with contact information or a website for customer support.

M—Monitor Response. Nutritional supplements can take effect immediately or might require prolonged administration prior to having a notable response. Always watch for adverse effects.

A—Avoid Double Dipping/Mixing. Many drug-nutrient interactions can affect the way horses’ bodies metabolize exogenous substances. Offering several medications or supplements might result in unexpected side effects.

R—Re-evaluate Your Choices. If the product is not having the expected effect, consider alternate dosing, sources, or management strategy.

T—Talk to an Expert. Always consult your veterinarian before using any new supplement.

Originally designed for joint supplements, these strategies can be adopted to any nutritional supplement to help horse owners get the most bang from their hard-earned bucks.

Q: I often hear the term “essential nutrients” from equine professionals, but I’m not sure what that means or how it affects the way I feed my horse. Can you explain what essential nutrients are and how they should factor into my horse’s diet?

A: Essential nutrients are those we need to provide in a horse’s diet because his body either cannot synthesize them or cannot produce them in adequate amounts. These nutrients support overall health and help prevent deficiencies.

Horses need essential nutrients from six categories: water, carbohydrates, fats, proteins, vitamins, and minerals. Authors of the Nutrient Requirements of Horses, 2007 (NRC) detail the recommended amounts of each essential nutrient to prevent deficiencies, based on the current scientific knowledge.

For example, nutritionists consider vitamin E essential because horses cannot synthesize it in the body, so owners need to supply it in the diet. In contrast, vitamin C does not have a defined dietary requirement because horses can synthesize it from glucose, which experts assume meets their needs.

Following the NRC guidelines will help ensure your horse’s diet meets his nutritional needs. However, it can be confusing and overwhelming to calculate these numbers for your horse’s feed. Luckily, equine nutritionists have already done this work for you.

Nutritionists designed commercial feeds from reputable companies to meet these requirements if fed at the manufacturers’ recommended rates. Ration balancers, performance feeds, and lifestyle feeds can meet your horse’s nutritional requirements when you feed them alongside adequate forage and salt.

Start formulating your horse’s nutrition program by feeding forage at about 2% of his body weight on a dry matter basis. Then choose a fortified feed to cover any nutritional needs the forage doesn’t meet.

The type of concentrate feed you choose depends on your horse’s body condition and workload. For example, a mature horse that readily maintains his weight on forage would be a candidate for a ration balancer. However, a performance horse that is a harder keeper might need a concentrate that also provides supplemental calories. Again, always feed the product at the recommended rate to ensure it meets your horse’s nutrient requirements. If you feed less than the recommended rate, check the label for instructions on combining it with a ration balancer or consult a qualified equine nutritionist to adjust the diet appropriately.

Researchers continue to investigate and define the full range of essential nutrients horses need. For example, horses need amino acids, or the building blocks of protein. There are 21 amino acids, 10 of which are essential. However, researchers have only established a documented requirement for one essential amino acid—lysine. Ideally, we’d have established a requirement for each of the 10 essential amino acids, but that research has yet to be done.

Take-Home Message

To support your horse’s health, feed the recommended amount of each essential nutrient daily as described by the NRC based on the current scientific understanding. Feeding adequate forage, providing salt, and offering a commercial feed at the manufacturer’s recommended rate can effectively meet your horse’s essential nutrient requirements. An equine nutritionist can also help you balance your horse’s diet and be sure his needs are met.

Horses need a variety of minerals to support their daily nutritional requirements. These minerals play important roles in the body, from providing antioxidants to comprising key elements of bone. Without the right minerals, horses can develop health issues such as skin and coat problems or lack of muscle development. Ensuring your horse’s ration adequately provides him the essential minerals in the right amounts is imperative to his health and well-being.

How to Know if a Horse is Getting Enough Minerals

Accurately evaluating your horse’s mineral status is important because it can take many months for the health issues that arise from improper supplementation to become apparent. “Given that it isn’t possible to look at a horse and know whether you are providing the right amount of minerals just based upon the horse’s appearance until deficiencies or toxicities are pretty severe, the best approach is to know what your horse requires and determine if what you are feeding it meets the requirements,” says Brian Nielsen, PhD, MS, PAS, Dipl. ACAN, animal science professor at Michigan State University, in East Lansing.

The best way to determine your horse’s mineral needs is to have a nutritionist complete a full dietary evaluation, says Shannon Pratt-Phillips, MS, PhD, PAS, a professor in the Department of Animal Science at North Carolina State University, in Raleigh. First, obtain a hay analysis; because forage is the base of your horse’s diet, evaluating the quality of his hay will allow you to fill in the remaining mineral gaps with a concentrate or high-quality ration balancer. “Unfortunately, other tests, like hair or blood, are not very useful for measuring mineral status in the horse, so analyzing the full diet is the best way to ensure that your horse is meeting its needs,” she says.

Ideal Mineral Ratios in Horse Diets

Amounts of minerals are important when meeting your horse’s nutrient requirements, but don’t forget to consider mineral interactions. “When one mineral can affect the absorption of another mineral, we might need to establish a ratio to ensure that a particular mineral is not fed in amounts that might inhibit the absorption of another, even if the other mineral is fed in the correct amounts,” says Pratt-Phillips.

The most frequently discussed mineral ratio in equine nutrition is calcium (Ca) to phosphorus (P). “While many horse owners are taught that a ratio of 2:1 (2 parts Ca to 1 part P) or 1.5:1 is the ratio for which we should strive, it really isn’t critical that it is precisely that ratio,” says Nielsen. “As long as there is more available calcium in the diet than there is available phosphorus, there are typically no concerns. By contrast, a ratio of 1 part calcium to 1.2 parts phosphorus would be a real concern.”

A skewed ratio can cause the body to sense a calcium deficiency, even if the amount in the diet is adequate. “When there is a perceived calcium deficiency, there is a release of parathyroid hormone,” says Nielsen. “The result is calcium being released from bone in order to maintain blood calcium. Doing so can result in the condition known as nutritional secondary hyperparathyroidism (also known as big head disease) in which the bone is weakened.”

In addition to calcium and phosphorus, zinc (Zn) to copper (Cu) and iron (Fe) to copper to zinc to manganese (Mn) are important ratios to consider. “There is no published scientific research that supports the claims for Zn:Cu or Fe:Cu:Zn:Mn. Rather, it is just important that you are meeting the requirements, and it is also wise to avoid over supplementing minerals,” says Nielsen.

“I would be very wary of increasing other minerals simply to try to achieve some kind of ‘ratio’—for example, if iron is too high, we shouldn’t try to feed more copper or zinc to accommodate for that,” says Pratt-Phillips. “Research has shown that over supplementing minerals winds up in waste and, ultimately, in groundwater, and could be bad for the environment.”

Knowing When to Add Minerals to Your Horse’s Diet

The National Research Council’s (NRC) Nutrient Requirements of Horses, published in 2007, provides recommended intake levels of the necessary minerals based on your horse’s body weight and workload. “It is important to know the nutrient composition of what your horse is eating from all parts of their diet—that includes from forage, concentrates, and supplements,” says Nielsen. “It is easy to have hay analyzed for nutrient composition, and that is the only way to know what it provides.”

Many horse owners who receive different hay regularly might not invest in the analysis. “I would argue for even that one point in time, it is worth investing the extra $20-40 to get the hay analyzed to check the mineral status in the hay,” says Pratt-Phillips.

If your horse’s diet is primarily hay with an additional concentrate and/or supplements, again, a complete hay analysis will provide quality information for your nutritionist to help you develop a balanced diet for your horse. If you horse consumes pasture, evaluating the mineral content can be a bit more challenging. Nielsen suggests consulting with a local extension agent to find out if there are any known soil deficiencies in the area (such as selenium).

By calculating the total amount of minerals your horse consumes and comparing it to what the Nutrient Requirements say he needs, you can determine if your horse’s diet is sufficient.

Available Mineral Sources for Horses

Minerals included in your horse’s diet can be offered in organic or inorganic form. “Technically, in chemistry, ‘organic’ refers to being carbon-based, this meaning carbon is part of the molecule,” says Nielsen. “However, in popular culture, organic is often used to signify ‘natural’ and is a term that is widely used when marketing, as people believe it is better—rarely is there any evidence that such is the case. Ironically, with minerals, the inorganic tends to be natural, and the organic minerals tend to be synthesized or manufactured.”

A horse’s mineral requirements are based on his ability to digest and absorb them, so it is important to understand the differences in bioavailability between sources. “Organic sources of minerals are likely more bioavailable, so the horse may actually need less of them,” says Pratt-Phillips. “A good nutritionist will be able to pick out some of these ingredients in feed tags, and this could affect how you interpret a dietary analysis.”

Take-Home Message

Ensuring your horse receives appropriate amounts and types of minerals is a key consideration when developing a balanced diet for your horse. Both over- and undersupplementing certain nutrients can cause serious health problems, but clinical signs might not show up for months. Analyzing hay and consulting a qualified equine nutritionist to review your horse’s mineral intake can help you ensure your horse receives the correct nutrition from his diet.

Researchers continue to learn how the components of a horse’s diet can help battle inflammation

Human nutritionists and doctors often encourage patients to consider diet changes to avoid or reduce inflammation. A list of healthy eating tips from the University of California, Davis, suggests eating more fiber and high-fiber carbohydrates, among other things.¹ Researchers from John Hopkins Medicine and Harvard Health suggest adopting a Mediterranean diet because it is based on omega-3 fatty acids, vitamin C, and fiber-rich foods.^2,3

Increasingly, horse owners want to know if dietary changes can help reduce or avoid inflammation in their horses, too. Researchers continue exploring the link between nutrition and inflammation in equine medicine. Despite progress, gaps remain in understanding how diet influences inflammation—both positively and negatively.

“My big caution to horse owners is not to assume that just because it works in a human that it’s going to work in a horse,” says Sarah H. White-Springer, PhD, associate professor of equine physiology at Texas A&M University, in College Station. “We expect it to be similar because horses are monogastric, and so digestion and absorption that happens before the hindgut, where all the microbes live, should be similar. What we’re finding is sometimes that’s not exactly true.”

That said, a growing body of data, especially related to antioxidant supplements and nutrients such as vitamin E, selenium, and vitamin C, show correlations between nutrition and inflammation. Here we’ll provide a look at what experts know so far.

Understanding Inflammation in Horses

Inflammation is the body’s response to injury, infection, or stress. Jessica Suagee Bedore, PhD, associate professor of practice in the School of Animal Sciences at Virginia Tech, in Blacksburg, says that it’s critical to recognize that inflammation is not always harmful. It’s part of the body’s natural response to stressors such as exercise.

“In normal inflammatory processes, inflammation is important for clearing damaged tissue, and anti-inflammatory processes should take over after inflammation has done its job,” she says. “So, we don’t want anti-inflammation too soon.”

White-Springer agrees some level of inflammatory response plays a necessary role in triggering adaptation. “Simply reducing inflammation may not be the best approach because it could be detrimental to the horse’s ability to adapt to stressors,” she says. “So, we need to be careful about blunting the inflammatory response entirely.”

She says measuring subclinical or cellular-level inflammation in horses presents a major challenge. The difficulty arises because outward signs of inflammation aren’t usually visible without a significant injury.

“Our lab is trying to identify or quantify subclinical inflammation—inflammation that might be happening at the cellular level, but maybe that we can’t see on the outside yet,” White-Springer says. “I think if we can answer ‘How do we define inflammation, before we can see it?’ then we can start to investigate, ‘What are the things that can improve that inflammation or mitigate that inflammation?’”

Ingredients That Tend to Have Anti-Inflammatory Properties

Kathleen Ivester, equine research scientist in the Department of Veterinary Clinical Sciences at Purdue University College of Veterinary Medicine, in West Lafayette, Indiana, says polyunsaturated fatty acids (PUFAs) play a crucial role in managing inflammation. The balance between omega-6 and omega-3 fatty acids significantly influences the body’s ability to regulate inflammation.

“The omega-6 fatty acids are converted arachidonic acid, the precursor to many inflammatory mediators including prostaglandins,” she says. “In contrast, omega-3 fatty acids are converted to molecules that promote the resolution of inflammation. The same pathways use omega-6 and omega-3 PUFAs as starting material, so the balance between the two is very important. Diet determines how much omega-6 and omega-3 PUFAs are present.”

Researchers from Purdue demonstrated that the type, quality, and feeding methods of forage impact respiratory tract inflammation in horses. This occurs both due to variations in dust exposure and nutrition.

“We have found a strong benefit of supplementing DHA (docosahexaenoic acid) or EPA (eicosapentaenoic acid) and DHA together in a few randomized controlled clinical trials,” says Ivester.  “We have been surprised at how quickly we see improvement in coughing and in the amount of inflammation in the lung.”

Suagee Bedore added that omega-3 fatty acids—particularly EPA and DHA—have been studied in horses in disease states beyond respiratory tract inflammation.

“Because these are the precursors of metabolites used in the inflammatory cascade, we know their cellular function in anti-inflammatory processing,” she says. “There are probably at least a dozen other nutraceuticals, including vitamin E, curcumin, Cannabis sativa, and resveratrol. But I encourage each owner to read original research, at least the abstract, to check the dosing and which disease the nutraceutical was tested in.”

Juliet M. Getty, PhD, owner of Getty Equine Nutrition LLC, in Denton, Texas, says “protein quality makes a difference in the horse’s ability to produce and repair tissue as well as keep healthy endocrine and immune systems.”

Ingredients That Tend to Aggravate Inflammation

Researchers have shown diets high in omega-6 fatty acids can promote inflammation. Corn and corn products serve as major sources of omega-6 PUFAs, Ivester says.

“Without a source of omega-3 PUFAs to balance this out, diets rich in corn products will tip the balance toward inflammation  and may create a tendency for chronic inflammatory conditions, including but not limited to asthma,” she explains.

Getty added that excess glucose in the diet can also trigger inflammation. “Insulin is a highly inflammatory hormone,” she says. “Finding forages that offer less than 10% ESC and starch, on a dry matter basis, will help your horse support a healthy weight and avoid the oxidative stress that comes with insulin resistance.”

Getty says excessive production of free radicals and too few antioxidants present to neutralize those free radicals cause oxidative stress. When this imbalance exists, tissues sustain damage. As a result, the cells can no longer behave properly, and disease results.

Equine Gut Health and Inflammation

Anti-inflammatory medications represent one of the biggest risk factors for gastric ulceration in horses. Ivester says a diet that promotes inflammation resolution while minimizing the need for pharmaceutical intervention would likely reduce the risk of gastric ulceration.

She notes that the research she has seen suggests diets deficient in omega-3 and high in omega-6 PUFAs not only predispose a horse to inflammation but also are detrimental to the gut microbial population. This further increases the risk of chronic inflammatory conditions.

Getty added that a horse lacking fiber in his diet could suffer from severe inflammation in the entire digestive tract, including ulcers, leaky gut, fecal water syndrome, and inflammatory bowel disease.

“The diet must be forage-based with supplementation to fill in the nutritional gaps that exist with hay,” she says.

“Concentrates can provide added vitamins/minerals, protein, and fat, but they must be fed according to directions to offer the proper amount of nutrients.”

When White-Springer designs a feeding program for horses, she says she starts with a forage-focused diet paired with turnout because horses graze and, when fed that way, tend to do better. She specializes in performance horses, where energy is the primary nutrient need that increases with exercise training.

“A lot of times people will automatically go to a concentrated grain product to add calories,” she explains. “My favorite product to add is beet pulp because it’s highly digestible for the horse, and it’s a fiber, and horses are naturally made to eat more fibrous foods.”

Also, feeding horses only twice daily, a common practice in many barns, might damage intestinal villi and contribute to leaky gut. Whenever possible, provide free-choice forage, though this might not be suitable for obese horses or those with equine metabolic syndrome. Discuss your horses’ specifics with your veterinarian.

Take-Home Message

Equine nutrition plays a crucial role in managing inflammation, but applying human dietary principles directly to horses can be misleading. Emerging research highlights the importance of balancing omega-3 and omega-6 fatty acids, incorporating antioxidants, and prioritizing a forage-focused diet to support gut health and reduce inflammation. Scientists continue to aim for a more tailored approach to managing equine health in their ongoing research.

This article is from the Older Horse 2025 issue of The Horse: Your Guide to Equine Health Care. We at The Horse work to provide you with the latest and most reliable news and information on equine health, care, management, and welfare through our magazine and TheHorse.com. Your subscription helps The Horse continue to offer this vital resource to horse owners of all breeds, disciplines, and experience levels. To access current issues included in your subscription, please sign in to the Apple or Google apps OR click here for the desktop version.

Q: My horse will be turning 20 soon, and my barnmate told me I need to be more cautious about how I feed him vitamins and minerals to ensure I meet his daily requirements. Will his requirements change as he ages? Are there any specific vitamins he might become deficient in? 

A: Just as a human’s nutritional requirements change as they age, so will your horse’s; however, working with your veterinarian and an equine nutritionist can help you ensure he is getting the nutrition he needs during his senior years. 

Vitamin C can be particularly interesting for senior horses. In a study that looked at physiologic differences between young horses and older horses, researchers found that older horses had lower vitamin C levels overall. Of course, horses are a species, unlike humans or guinea pigs or any other animals, that can actually synthesize their own vitamin C, so we don’t know if horses just can’t produce enough vitamin C, or perhaps they use more of it because it is a pretty powerful antioxidant. This might mean that it’s necessary to supplement vitamin C if you have an older horse. 

Just like if a child ate too many vitamin C orange-flavored vitamins, oversupplying most nutrients, including vitamin C, is not a major concern because these can be excreted through the urine. However, there are some theories that oversupplying some vitamins, such as vitamin C, could inhibit the horse’s innate ability to produce them, making continued supplementation necessary. 

As horses get older, they might also become deficient in vitamin E and require supplementation, especially if they have little pasture available to them. When evaluating your horse’s vitamin E levels, it is important to analyze your horse’s diet. However, you can also ask your veterinarian for bloodwork to ensure that your horse’s vitamin E status is good.

Vitamin E is relatively safe, even in higher doses, but it can potentially prevent the absorption of other nutrients if overfed in excessive quantities. Ultimately, working with an equine nutritionist to regularly evaluate your horse’s diet, and with your veterinarian to test your horse’s blood levels will help ensure that they receive proper nutrition as they age. 

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Q: My horse pastures have not been as healthy as I’d like, and I must feed my horse more hay than most people living in my area to be sure he’s getting enough forage. I know soil health is the first step to cultivating healthier horse pastures. How can I be sure my pasture soil is healthy and can support the grasses I want growing?

A: Healthy soil in horse pastures can allow grasses to function to their highest potential with minimal support, says Brad McIntyre, a farmer in Southwestern Idaho with productive organic pastures and an interest in soil health.

“Soil is part of a natural system, created way before us,” says McIntyre. “Animals are part of that natural ecosystem (too),” he adds, noting that their manure and urine help build a healthy pasture environment.

Here are McIntyre’s Top 4 tips for creating healthy horse pastures.

1. Grazing Height

Keep pasture grass at least 4 inches tall; don’t let horses graze them any shorter. Grasses shed roots—the roots change color from bright white to gray, then brown, and eventually black as the plant tissues die—and their roots are typically as long as the plant stand. If horses overgraze plants every day, the grass constantly sheds its roots, making it shorter. When horses overgraze a pasture, they often wipe out the desirable grass species, leaving room for undesirable species to take over.  

2. Compost

Compost provides a rich source of nutrients and beneficial microbes. Composting involves encouraging microbes to break down organic material into a soil amendment that acts as a long-term, slow-release fertilizer. On horse farms this typically includes animal manure, stall waste, and dead plant material. Compost manure and other organic matter on your farm and reapply it to your pastures to encourage beneficial plant growth.

3. Water

Water and sun can go a long way in improving horse pasture soil health. If you live in a hot and dry environment, you might need to irrigate your pastures to improve growth. But, if you add too much water, you might essentially drown the desirable grasses in your pasture. Plants prefer a heavy amount of water, then a period of rest to regrow. Typically, McIntyre irrigates for 24 hours every seven to 10 days.

4. Rest Pastures

Let your pasture rest and your grasses seed out after grazing periods. Then turn your animals back out to graze; as they move and eat, they’ll press the seed heads into the soil. In effect, you get a free reseeding. McIntyre aims to do this every few years.

Take-Home Message

Healthy soil drives better horse pasture growth. To protect it, make sure your grass stays a few inches tall. “Work with what’s free. It’s a natural system,” says McIntyre. Healthy soil leads to healthy pastures and, in turn, healthy horses and a healthier planet, he adds.

Q. This spring, I moved my horse to a new barn with grass turnout. My horse hasn’t been on pasture since I got him, and I’m unsure how to make this transition. I know it needs to be gradual, but how gradual, and how do I make it work?

A. I’m sure your horse will appreciate the opportunity to be turned out and have pasture access. But you are correct: Sudden dietary changes, whether it’s the introduction of grain, a hay change, or a move to pasture, can lead to colic and laminitis if done abruptly, whereas a gradual transition allows the digestive tract to adapt. The types and amounts of enzymes the horse’s digestive system secretes are diet-specific. This is also true of the bacteria composing the horse’s hindgut microbiome.

When equine diets change suddenly, feed components that should be digested and absorbed in the small intestine might not be. They might instead reach the hindgut, disrupting the microbiome microbial population. This can result in gas production, hindgut pH reductions (becoming more acidic), as well as die-offs of certain bacterial populations, causing toxin release. All of this can contribute to colic and laminitis.

Early spring pasture contains a lot of moisture, protein, and nonstructural carbohydrates (NSC). NSC includes sugar and starch, as well as more complex fructan sugars. High-NSC diets have two problems:

1. A sudden transition to a diet high in NSC can cause the hindgut disruption already mentioned, because sugar and starch that should be removed in the small intestine are not; and
2. For horses with metabolic issues such as insulin dysregulation and equine metabolic syndrome, NSCs can induce laminitis and founder.

To minimize hindgut disruption, a slow introduction to pasture is necessary, especially for sensitive horses with metabolic conditions. Understanding that these individuals might not be good candidates for any pasture is important. Before you embark on this project, make sure your horse is a good candidate for pasture.

If the barn manager expects pasture to provide real nutritional benefits, fields must be well-established before introducing horses. Putting horses on new pasture too early and before the plants are well-established can be tempting. Wait until the pasture has at least 6 inches of grass before grazing. A safe rule of thumb is that the bottom 4 inches always belong to the plant. If pastures are grazed below that height, you start to rob the plant of its ability to maintain itself, and ultimately your pastures will become overgrazed and plants will die, leaving bare patches and opportunity for weeds to take hold.

Assuming you have the minimum 6 inches of growth, introduce your horse to the pasture initially for just 15 minutes. This might require hand-grazing, because not all horses are going to want to come back inside after only 15 minutes on such a delicacy as spring grass! Then increase the grazing time by about 15 minutes every day until your horse is grazing for about four hours total. Stay at four hours per day for at least a week before granting unlimited access.

Clearly this process is labor-intensive, so it can be helpful to get creative about how you pull it off. The initial 15-30-minute periods can be fairly easily achieved before or after a ride. Allowing 15 minutes before a ride is a great way to get some forage in the stomach. If time is short, do your grooming while your horse grazes, or just hang out and enjoy his company. Then add some time after your ride as a reward. Schedule grazing so longer turnout periods happen on weekends or when you have more time. Ask a friend at the barn to help you out. With some teamwork and creativity, you can transition your horse to pasture safely.

Q: What are the best feeding practices to ensure a smooth weaning transition for the foal?

A: Suckling foals grow rapidly, with most reaching 30-40% of their mature weight by weaning. Development at this rate requires a steady supply of good nutrition. Mare’s milk primarily supplies a foal’s nutrition until weaning, after which the diet transitions to some combination of feed, supplements, and hay or pasture. You can make this transition easier by introducing appropriate feeding practices prior to weaning. What and how you feed the suckling foal will impact not only his overall growth and well-being but also how well he handles weaning.

Feeding Suckling Foals

Suckling foals show interest in eating within the first weeks of life. A foal feed should be formulated with high-quality protein to supply essential amino acids and be adequately fortified with the proper balance of vitamins and minerals. The goal of supplemental feeding for suckling foals is to bridge the gap between what the mare’s milk provides and what the foal needs to grow and develop to his full genetic potential. Feeding 1 pound of a well-formulated foal feed per month of age daily will help accomplish this. For example, a 2-month-old foal should eat 2 pounds of feed per day, or roughly 1 pound of feed per 100 pounds of body weight.

Feeding mares and foals individually—not in a group—offers the most precise method to feed the foal. However, many farms don’t have the staff or the facilities to do this. Creep feeders are an option but must be monitored to make sure mares cannot get the feed and to prevent injuries around the equipment. Creep-fed foals should be grouped and fed amounts appropriate for their age. If allowed free-choice feed, foals often overeat and gain weight too fast, putting undue stress on immature bones and joints.

Mares and foals are often fed together, which can work well. As the foal gets older and needs more supplemental feed, the mare’s nutritional demands for lactation begin to decline. When feeding mares and foals together, place feeders at a height the foal can comfortably access and be sure to allow plenty of space.

Feeding Foals After Weaning

Following weaning, feed foals the same concentrate they were eating prior to weaning, but increase the feeding rate to 1.25–1.75 pounds per 100 pounds of body weight to replace the mare’s milk. If possible, divide the daily ration into smaller, more frequent meals to help with the transition from having free-choice access to the mare’s milk and nursing over 70 times a day. Weanlings have small digestive tract capacity and benefit from smaller meals.

Forage quality is also important for weanlings because they have less capacity and ability to digest hay and pasture than an adult horse. If weanlings have free-choice access to excellent pasture or hay and would become overweight eating the recommended amount of the foal feed, you might need to transition them to a ration balancer.

A ration balancer is designed to be fed to foals as well as adult horses and will provide appropriate nutrition to support lean tissue development without unnecessary calories. Routinely assess your weanling’s body condition and adjust the amount of feed offered or transition to a ration balancer if needed to support moderate body condition. This will help ensure the nutritional requirements for growth and development are met without the youngster becoming overly fat.

Take-Home Message

Suckling foals grow rapidly and need a carefully managed feed program to support healthy development and ease the transition to weaning. While the mare’s milk is the primary nutrient source early in life, introducing high-quality foal feed helps fill nutritional gaps and prepares foals for weaning. After weaning, increase feed amounts as appropriate and offer frequent meals to ease the transition from nursing, support continued growth, and improve digestive health. Monitor your weanling’s body condition and adjust his diet as needed to help him grow correctly without becoming overweight.

Do you have an equine nutrition question?

Q. My horse gets frequent bouts of cellulitis. I work closely with my vet to treat and prevent this medically, but is there anything I can do to support our efforts through his diet?

A. Cellulitis is a bacterial infection that involves both the connective tissue and the fat tissue, most frequently presenting in the lower limb of the horse, and can be a challenging health issue. There are multiple causes of the condition; however, the infection normally enters the body through small (often undetectable) microtraumas on the skin surface.

Medical management is critical to resolving these cases, so it is great that you are working closely with your veterinarian. For treatment, the goal is to reduce the inflammation, eliminate the infection, and reduce the likelihood of the infection recurring.

A Balanced Diet for Horses With Cellulitis

Although nutritional management is not a cure for cellulitis, there are some dietary changes you can make to support your medical efforts. A balanced diet is imperative to maintaining both skin health and the immune system. Providing your horse with a feed or ration balancer (fed at the manufacturer’s recommended amount) is an important factor. Inadequate protein (amino acids), vitamin deficiencies, and unbalanced minerals can all negatively impact the health of a horse’s skin and hair coat, so pursuing a balanced diet for your horse with appropriate levels of vitamins, minerals, protein, and energy is important to promote optimal health.

Vitamin E & Omega-3s to Reduce Inflammation in Horses

When inflammatory issues are present, adding vitamin E and a source of omega-3 fatty acids is also a common recommendation. For your horse, if he is on a balanced diet, I recommend having his vitamin E levels tested via blood serum. If the levels are adequate, then there is no need for additional supplementation but, if he has a deficiency, supplementing with a natural source of vitamin E can help support your efforts to prevent cellulitis. 

When adding omega-3s, opt for a fat source that is greater in omega-3 content than omega-6 content (while one omega-6 type has been studied for its beneficial effects, omega-6s are generally considered to have pro- rather than anti-inflammatory properties; the ratio of the two seems to be what’s important). Oils such as flax or camelina are good options and can be fed at a rate of 1-2 oz per day to start and increased to 2-4 oz per day if your horse needs additional fat. Adding fat to the diet can help your horse maintain the protective barrier of sebum on his coat. This is especially important if your horse has dry skin and is prone to cellulitis. If your horse is not overweight, adding an omega-3-rich fat source to his daily ration can be a good way to support the prevention of cellulitis.

Digestive Support for Cellulitis

Because the cellulitis episodes are frequent, you could try a digestive support supplement for your horse. Regular administration of non-steroidal anti-inflammatory drugs (NSAIDs) and/or antibiotics can disrupt his gastrointestinal tract. Of course, a balanced forage-based diet will be a key factor in maintaining your horse’s gut health, but adding a pH control supplement for the gut could provide extra support. When choosing a supplement, evaluate the research on the product to ensure what you are investing in will support for your horse.

Take-Home Message

When cellulitis bouts occur, seeking medical management and guidance on optimal treatment from your veterinarian should be the first step. However, there are some nutritional considerations that can support your horse in addition to the medical efforts. A balanced diet that provides your horse adequate nutrients is imperative to his overall health. Adding a fat source that is rich in omega-3s and investigating digestive support supplements to use when your horse is on NSAIDs or antibiotics could reduce the negative effects these medications might have on his digestive system.

Do you have an equine nutrition question?

Q: With summer approaching, I want to be sure I’m prepared to minimize unpleasant odors on my farm that are always worse during the warmer months. What can I do to eliminate those odors or prevent them altogether?

A: During the warm season horse properties can develop odors—between muddy turnouts, stockpiled manure, and urine buildup in confinement areas. These spots attract pests such as flies and rodents and can raise concerns among neighbors. Inhaling ammonia in stalls, barns, or confined spaces can also harm a horse’s respiratory tract. Here are five tips to help you reduce odors on your horse property.

1. Start With Healthy Soil

Odor control starts with a step many people overlook: Start with healthy soils and slightly sloped ground. If you confine horses in a low, wet area you will end up with mud and odor problems. Make sure you have a good, even slope (about 1-2%) away from stalls or shelters. Be sure to grade the ground, making it even before putting gravel or another type of footing in these areas. Otherwise, any depressions in the underlying soil allow water (and urine) to pool under the gravel, potentially causing odors.

2. Develop a Manure Management Program

A solid manure management program goes a long way in solving odor issues. Begin by picking up manure every one to three days in confinement and high-traffic areas. Establish your manure pile far away from streams, ditches, rivers, or other bodies of water to prevent runoff contamination, and cover it with a tarp (to keep it from getting soaked by rain).

Let’s say you’ve picked up manure and you still have odors. The simplest and cheapest solution might be to drag or harrow the paddock. This helps get beneficial aerobic microbes back in your soil that break down tiny, odor-causing organics. It also helps the ground dry faster.

3. Minimize Moisture

Keep your farm as dry as possible by removing opportunities for standing water to form. Keeping shelters, stalls, and barns dry, or at least well-drained, goes a long way in reducing odors. Moisture often triggers odor problems; wet areas release more odor-causing compounds than dry ones. Consider doors, screens, or roof overhangs for shielding barn openings from rain. Invest in good working gutters and downspouts, which divert rainwater away from buildings and confinement areas. Ventilation also helps dry the barn area by releasing and not trapping moisture and allowing odors to dissipate. Stall windows, open doorways, cupolas and vents in roofs, ceiling fans, etc., can all improve ventilation in your barn.

If a horse perpetually urinates in one spot in a confinement area, you might have to occasionally dig out and refresh footing in that spot to help it dry thoroughly.

4. Use Microbial Sprays to Minimize Odors

A variety of microbial spray products are available, which you can use on urine spots and across confinement areas to neutralize odors. These products contain different types of beneficial bacteria, enzymes, and/or fungi. They come in highly concentrated solutions that you dilute and spray on paddock areas with a garden sprayer. The beneficial microbes break down ammonia and organic material that cause odors and attract flies. Use these animal-safe solutions as often as needed to control odors. You can commonly find these beneficial microbial sprays at organic garden supply companies or feed stores.

5. Use Zeolite Products in Stalls

Zeolite products remove odors effectively when you sprinkle them in stalls or other areas of your barn. These naturally occurring minerals have a highly porous structure, which binds with ammonia molecules in urine, eliminating odors. You’ll find zeolite, which looks like finely ground kitty litter, in several stall deodorizer products.

Take-Home Message

Starting with healthy soil, developing a manure management program, minimizing moisture, and using microbial sprays and zeolite products can all help reduce the odors on your horse farm. In turn, this will minimize pests and support your horses’ comfort and well-being.

Q: I have a 20-year-old Arabian/Paint gelding that I’ve had since he was 3 months old. He was always an easy keeper and I realized when he was around age 4 or 5 that he had equine metabolic syndrome (EMS).

From that day on, he’s consumed low-nonstructural-carbohydrate (NSC) hay and grain. Because he is an air fern, I’m always careful about what he eats and severely limit his grazing time; I keep him on a dry lot most of the time. At age 14 he developed pituitary pars intermedia dysfunction (PPID, formerly called equine Cushing’s disease). My veterinarian put him on 1.5 Prascend (pergolide) pills per day, which I administer in addition to Thyro-L (levothyroxine sodium).

Somewhere during all of this, my gelding started losing weight. He had a mild gastric ulcer attack a few years ago, so my veterinarian prescribed ranitidine, which she later replaced with cimetidine. Recently, he had another ulcer attack and currently has omeprazole added to his diet. My question is, how do you feed PPID, EMS, and ulcer-prone horses that need to gain weight? I already feed every four to five hours. Consuming oils never helped him, but soaked beet pulp has helped some.

A: Hello, I am sorry you’re having to handle these difficult issues. The first thing I recommend is having a good discussion with your veterinarian about your horse’s conditions to determine whether the current medications should stay the same or be adjusted. Veterinarians often prescribe Thyro-L to help horses regulate glucose and insulin and treat EMS. They also commonly prescribe Prascend, which you also mentioned, for horses with PPID. Both medications can cause weight loss—a side effect that usually benefits horses with EMS and PPID. However, your veterinarian might want to monitor the dosage and make adjustments if needed.

I am glad to hear your horse receives omeprazole for his ulcers. Currently it is the only FDA-approved medication for treatment and prevention of gastric ulcers in horses. I recommend talking with your veterinarian about whether you can discontinue this medication or reduce the dosage once management strategies help get the condition under control.

I would like to address feeding management of the three distinct disorders you mention—EMS, PPID, and gastric ulcers. Fortunately, some of the recommendations for managing these conditions overlap, which can make caring for your horse easier.

EMS

Horses with EMS tend to be easy keepers and carry extra weight, but you need to make sure you aren’t “starving” them to get them to an ideal weight. Forages low in NSCs should be the base of their diet. Typically, they should have only hay with little to no access to pasture, especially in fall and spring when pasture NSC levels tend to be higher. On a per-pound basis you’ll want to avoid feeding less than 1.5% of a horse’s body weight in hay. A low-calorie/low-sugar ration balancer can help you make sure you meet all his nutritional requirements. To help keep glucose and insulin levels steady, provide small, frequent meals and/or use a grazing muzzle to slow down feed intake.

PPID

Pituitary pars intermedia dysfunction cannot be managed with diet alone (hence, giving pergolide), but it can help. Overweight horses should receive a lower-calorie diet to promote weight loss, and horses with insulin resistance or insulin dysregulation (often referred to together as EMS), need a diet low in NSCs. If a horse with PPID has not been diagnosed with EMS, you can generally feed a balanced diet of forage and concentrates or a ration balancer, while monitoring weight to prevent excessive gain.

Gastric Ulcers

For horses prone to gastric ulcers, feeding recommendations try to decrease acidity (low pH) in the stomach. Horses are designed to be continuous feeders; some type of feed is in the stomach almost constantly. We can mimic this by providing horses with multiple small meals throughout the day and allowing free-choice access to forages. Nutritionists also recommend reducing the amount of concentrate a horse receives to address gastric pH. Higher-fat feeds tend to slow gastric emptying rate and are not as acidic as more traditional concentrates. Experts also suggest offering some feeds on the market that contain more complex carbohydrates. Adding a forage higher in calcium might also be beneficial, because it works as a natural antacid.

With both PPID and EMS the goal is to keep insulin levels regulated and maintain a horse’s body weight at a level that won’t predispose him to bouts of laminitis. I recommend you feed a good-quality mostly grass hay with an NSC level of less than 10%. If you can’t find hay with NSC levels below 10%, soak the lowest-NSC hay you can find for about 30 minutes prior to feeding to help reduce the sugar and starch content. Remember that you should not give your horses access to the soaking water because it will have all those undesirable carbohydrates in it. You should feed your horse about 2% of his body weight in forage daily—so about 20 pounds of hay for the average 1,000-pound horse.

I would also recommend a ration balancer if your horse maintains his weight on forage alone. Essentially, manufacturers design balancers to work as a vitamin and mineral supplement to ensure your horse gets the correct levels he needs. Make sure it is low in soluble carbohydrates. If he cannot maintain his weight on forage alone, then I recommend one of the higher-fiber feeds available. You mentioned your horse has consumed beet pulp, and it helped, whereas fats did not. Fortunately, many of these feeds have a beet-pulp base. These recommendations also work for the ulcer-prone horse, so they might help there as well.

It sounds like you are already taking many of the right steps for managing a horse with these three issues. Keep feeding meals more frequently and make sure you’re using low-NSC forages and feeds to maintain an appropriate body weight for your horse. I would be interested to hear what your veterinarian recommends related to the medications, and I wish you the best of luck.

Do you have an equine nutrition question?

To prevent feed degradation, mold growth, or contamination, owners should obtain and preserve the safest product

Poised on a Peruvian hillside sits a cavelike construction that once held a cache of food to supply an entire village. The steady cool temperature and darkness preserved it from rapid decomposition—a practice of storing food that developed over millennia. But in today’s world, on a moment’s whim, we find what we need at the supermarket, the farmer’s market, or in our backyard garden, with little need to keep substantial quantities of food on hand. When it comes to stocking up on feedstuffs for our horses, however, we still rely on storage and preservation lessons learned through history and science.

Ideally, owners should obtain the safest product and preserve it for feeding throughout the year, preventing feed degradation, mold growth, or contamination that could harm their horses.

Hay Storage

In much of the United States hay only grows during temperate months. The best quality is obtained and the best prices achieved by putting up a supply that will last until the next harvest. To keep stored hay as fresh and palatable as possible, focus on preventing mold development, heat buildup and combustion, and nutrient deterioration.

Proper hay harvesting and drying is important to control “respiration,” a naturally occurring process that produces heat and bacterial growth. Michael Collins, PhD, former professor of agronomy at the University of Kentucky, describes some of the science behind hay production: “Hay crops generally contain around 80% moisture at the time of cutting; field curing reduces moisture to levels (at which hay) can be safely stored. Hay cured to less than 16-20% moisture stores well with minimal problems of heating or mold growth. However, if baled with too much moisture (25-35%), microbial activity generates significant amounts of heat. In extreme cases, hay can reach spontaneous combustion temperatures.” Hay heated to 150-175°F has the potential to burst into flames, posing great danger to a horse facility.

In the initial weeks following baling, moisture and heat combine to maximize combustion risk. Thus, Kathleen Crandell, PhD, of Kentucky Equine Research, advises horse owners to monitor moisture levels (keeping them below 14%) and heat for two weeks after stacking new hay. They can achieve this by inserting an electronic probe (Delmhorst, for example, to measure moisture) and a temperature probe into bales to ensure temperatures remain below 120°F. If you come across hotter bales, remove them from the stack and spread them out in an area protected from rain to allow drying.

After buying properly cured hay, store it in a building separate from the barn with a leak-free roof. And, to thwart wicking of ground moisture into bales, Collins says to place bales on a layer of loose straw, crushed gravel, or wooden pallets. Otherwise, condensation forming beneath bales sitting directly on dirt or concrete can lead to mold growth and spoilage.

Crandell recommends stacking hay so air can circulate freely to evaporate moisture. “Stack square bales on edge, leaving narrow gaps between rows, alternating bale orientation in each layer and stacking no more than four or five bales high,” she suggests.

More horse farms are using round bales as an economical, less labor-intensive way to feed hay. Crandell suggests these bales be well-dried before stacking, as well.

Ventilation and air circulation also are essential in lofts, where hay is particularly prone to hazards of heat and spontaneous combustion. Follow Crandell’s recommended stacking regimen, refraining from stacking bales tightly or all the way to the ceiling. Lofts also tend to accumulate dust, which can build up on hay and cause respiratory problems for horses.

Protect hay stacks stored outdoors with well-secured waterproof tarps or other coverings that will withstand wind, rain, sun, and snow. Canvas tarps are superior to plastic covers, which are prone to punctures and leaks. Exposure to air (causing oxidation), sunlight, and weather extremes also subjects hay to nutrient loss. “Vitamin deterioration is inevitable, beginning the minute forage is cut in the field,” says Crandell. “As much as 75% of carotenes (vitamin A) diminish in the first 24 hours. Even under ideal storage conditions, more than 5% of vitamins are lost each month, possibly necessitating supplementation with a vitamin/mineral mix, ration balancer, or commercial concentrate.” Perform a hay and/or pasture nutrient analysis to determine supplement needs.

Stored Forage-Related Health Concerns

It is also important to consider potential dangers lurking in the hay and other stored forages themselves. Consuming as few as three to six blister beetles in legume hay (such as alfalfa or clover) can kill a horse. These insects often reside in hayfields and can be killed and baled during harvest. “(Owners are) less likely to encounter blister beetle problems in spring or early summer first-cutting hay since they are attracted to flowering plants that often coincide with late summer cuts of alfalfa,” says Collins. “Pre-bloom cut hay is less likely to be infested.”

Blister beetles might be more prevalent during years with bumper crops of grasshoppers, since they also feed on grasshopper larvae.

Hay poses another health threat: Horses might ingest spores of the botulism bacterium, Clostridium botulinum. “While not as common in hay as with ensiled feeds (i.e., haylage), botulism is usually associated with the presence of dead animals caught up in hay during baling,” explains Crandell. “It also occurs from ingestion of contaminated soil baled with trampled forage. An environment conducive to C. botulinum also promotes mold growth, yet another reason not to feed moldy hay.”

Haylage is high-moisture hay that has been compressed and encased in plastic within hours of harvesting. This processing environment couples high moisture and anaerobic (not requiring oxygen) fermentation, which can encourage proliferation of C. botulinum. “Moldy or discolored haylage should not be fed,” says Crandell.

She recommends inspecting hay and haylage carefully before feeding and disposing of suspect material. “Inspection can be difficult with round bales, but with availability of adequate forage, horses tend to eat around bad hay due to poor palatability,” she says.

Grain and Supplement Storage

Moisture is the enemy when storing forage or grain-based feeds, as well. To decrease the risks of decomposition and mold development, Crandell counsels owners to keep feed in cool, dry environments, with containers tightly closed to seal out moisture, insects, or rodents. Just as with forage, oxidation affects short-lived vitamins, particularly B-vitamins such as biotin.

Exposing cereal grains (oats, barley, and corn, for example) to high humidity or moisture can lead to mycotoxin production, which can have dangerous health consequences for horses. “Various mycotoxins are produced from fungi present at grain harvest that proliferate in the presence of moisture or humidity during storage,” Crandell explains. “Very small amounts of mycotoxins won’t usually affect a horse. A recent survey found these present in over 80% of grains. With (consumption of) significant mycotoxin levels, reduction in feed intake may be the first sign of a problem.”

Often, fungi are neither visible to the eye nor with a black light. “Some describe a pinkish, reddish hue to some corn kernels,” Crandell adds. “The only way to accurately test is to submit the sample to a lab. Moldy-looking feed may or may not be contaminated (with mycotoxins) but should not be fed to horses under any circumstance.”

A horse consuming moldy corn is at risk of developing liver failure and a serious neurologic condition called equine leukoencephalomalacia (ELEM, or moldy corn poisoning) caused by the mycotoxin fumonisin. Conditions that favor fumonisin growth on corn include a humid climate and a dry summer, followed by wet weather at harvest time. “During years of questionable corn harvests,” explains Crandell, “safe recommendations limit corn concentrations (in feed recipes) to less than 20% along with heating of corn through steaming, pelleting, or extrusion.”

All grains—not just corn—are subject to mold and mycotoxin development. Crandell reports that Aspergillus fungi produce alfatoxins in cereal grains; at high levels, these too are detrimental to horse health.

Stored Grain Longevity

Crandell explains that feed companies generally designate expiration dates within 30 to 60 days after grain product manufacture. If owners maintain feed under ideal circumstances, it might remain safe for four to six months, with straight whole grains (unprocessed, uncrimped) potentially lasting years, she says. Feed should contain few broken kernels, be kept in low-moisture (less than 13%) conditions, and safeguarded from insects and rodents. Humidity and temperature of storage facilities, degree of rodent or insect infestation, and exposure to air impact shelf life. “Store bags on pallets and try not to stack them more than five high, especially in humid climates,” says Crandell. “Sealed bags last longer than open bags. Once a bag is open, the clock starts ticking with quality of feed subject to degradation from exposure to air, humidity, and heat.”

She notes that adding molasses and/or oil to grain mixes increases moisture levels and can also affect shelf life. And high-fat feeds are more prone to rapid spoilage from the oxidation that degrades fats and fat-soluble vitamins (and causes them to go rancid). “Manufacturers add preservatives to slow oxidation, mold, and bacterial growth, but this doesn’t prevent deterioration, which is determined by storage conditions,” Crandell says. With rising temperatures and humidity during summer months, a feed’s shelf life decreases. Thus, Crandell advises keeping on hand only as much grain as can be fed within three to six weeks, or, if purchasing large volumes at one time, installing air conditioning in storage rooms.

Pelleted feeds’ shelf life might be longer not only because of lower moisture content but also due to heat treatment associated with pelleting. “Textured feeds usually include pellets containing the ‘loose’ particles (protein source, minerals, vitamins, yeast),” Crandell observes. While pellets generally last longer, other ingredients in a feed mix can shorten the shelf life. “Pellets are mixed with grains, beet pulp, and molasses—moisture differences and quality of all constituents affect shelf life,” she says.

Pest Protection

Fewer moisture-related problems arise when storing feed in breathable paper bags or wooden bins; however, these are not necessarily pest proof. Metal or hard plastic containers with secure lids reduce losses and spoilage, as well as prevent contamination with pathogens that pests can introduce such as Sarcocystis neurona (which causes equine protozoal myeloencephalitis, or EPM) or leptospires (causing leptospirosis). Horses can develop EPM from ingesting feed containing opossum feces. They contract leptospirosis by ingesting feed contaminated with infected mammals’ urine. Discard forage or grain that has been soiled with pest urine or feces. The best prevention is to store feed where rodents or other varmints can’t access it.

Plug rodent-sized holes in a feed room with steel wool or mesh to discourage mice; scattering sheets of fabric softener around the area also can achieve this. Use a feed storage container made of a material that rodents can’t chew their way into, and seal it securely with a lid that raccoons and other dexterous critters can’t open. “Galvanized metal trash cans effectively deter rodents,” says Crandell. “Since warm air hitting cold metal causes condensation inside that increases the chance of mold, these work best when kept in a temperature-controlled room.” She notes that metal-lined wood bins might also prevent rodent damage; however, wood does little to discourage insect intrusion or prevent spoilage from air exposure.

Moisture encourages not only mold growth but also insect proliferation within grain kernels. “Insects (weevils, grain mites, or beetles) eat grain from the inside out, removing nutrients,” says Crandell. “As with broken grain kernels, insect breakdown opens up grains to oxidation and mold growth, leading to a stale smell and significant decrease in palatability.”

Pest protection isn’t the only critical element of animal-proof feed storage: It is important to secure grain and supplement containers in a locked room or bin that can’t be accessed by a horse that has escaped from his stall or paddock. Unhindered access to feed can mean a very sick horse. Also to that end, on horse farms with small animals, chickens, ducks, or other livestock, take additional precautions to lock their feed supplies away from horse access.

Take-Home Message

Storing forage and grain properly helps maintain nutrient content and feed palatability. Critical aspects of safe storage include keeping feed in cool, dry locations to avoid moisture accumulation. Also remember that starting with a quality feed contributes to your feed stores’ longevity and nutritional impact.

Q: This time of year, my horse’s mane and tail get very dry, and even his coat seems dry. I use coat conditioners when I bathe him, but I’m wondering what I could do nutritionally that might help?

A: If you live in a hot, dry climate, preventing a dry mane and tail and coat can be challenging. I find this to be especially true of horses living in dry lots or with dirt runs where they are basically rolling in dust.

Other than using topical products to try to maintain coat quality, the best you can do is to give the horse’s skin and coat a fighting chance by ensuring you’re feeding all the building blocks needed to maintain skin and coat health.

Minerals

Key nutritional players in this arena are zinc, copper, fatty acids, and biotin. Zinc is vitally important to a number of enzymes in skin. Epithelial cells that make up skin require zinc for reproduction, maintenance, and repair. Additionally the synthesis of keratins (proteins that protect epithelial cells and that are found in hair) and other associated proteins rely on zinc for proper function. While zinc is found in forages, the amounts present might not meet your horse’s needs.

Copper is generally in even shorter supply in forages than zinc. Copper is necessary for the enzyme lysyl oxidase, which in turn is required to maintain the structural integrity of the cross-linkages that provide strength to collagen in the skin.

Together copper and zinc impact melanin, the protein responsible for hair pigmentation. Therefore, inadequate copper and zinc status might not only impact the keratinization of hair but also its color. Hair is at greater risk of oxidative damage if melanin is inadequate.

If you’re just feeding forage, consider adding a source of copper and zinc that provides about half of the National Research Council’s daily requirement, which for a 1,100-pound horse is 50 milligrams of copper and 200 milligrams of zinc. My preferred method is using one of the quality ration balancing feeds and supplements available on the market because they also supply other essential nutrients that might be missing in a forage-based diet.

If you’re already feeding a commercial feed, make sure that you’re following the feeding directions and offering adequate amounts, otherwise your horse might have deficiencies in nutrients key to coat quality.

Fat

The cell membrane layers that connect the cells that make up hair contain large amounts of fatty acids. The fat in the cuticle cells make them hydrophobic, meaning they don’t attract water. This acts to make them waterproof but also keeps moisture in. Cuticle cells should lie flat like shingles on a roof, but if they become damaged, they peel away from the hair allowing internal moisture to escape.

Therefore, ensuring adequate amounts of essential fatty acids in the diet might help improve coat quality. I particularly like sources of supplemental fats that provide more omega-3 fatty acids than omega-6, such as flax or camelina. For coat improvement purposes, I find plant-based sources to be more than adequate, and about 4 ounces of flax seed or 2 ounces of the oils should be enough for you to see an improvement in an average-sized horse.

Biotin

While we typically think of biotin in relation to hoof health, biotin also plays a role in skin and coat. Biotin is a B vitamin that is actually made by the bacteria in the horse’s hindgut making biotin deficiency unlikely.

However, in other species inadequate biotin results in poor quality skin and coat. This makes sense when you consider that biotin involved in fatty acid synthesis, amino acid metabolism, and a range of other metabolic pathways. While there are no guidelines for how much biotin to supplement to see improvement in coat quality, research suggests 20 to 30 milligrams for and average-sized horse to aid in hoof quality and we can assume similar levels are necessary to see coat improvements.

Take-Home Message

Ensuring that your horse has the building blocks necessary to create a healthy coat from the inside is your best way to defend against a dry coat. However, make sure that you are not shampooing your horse too frequently as this can remove naturally occurring oils. Additionally, look for simple shampoos that contain few detergents and avoid those with alcohol as these can strip the oils from a horse’s coat.

Q: I have a smaller horse farm with five horses on it. What can I do to reduce the amount of manure on my farm so it doesn’t create an eyesore or attract unwanted insects?

A: According to the USDA, one horse produces 50 pounds of manure per day. If you add spent bedding to that equation, you can have a huge mountain of stall waste daily just from one horse, not to mention several horses. However, you can find ways to use that waste, turning it into a resource for you, your community, and the ecosystem around you.

For horse owners with pasture or cropland, composting is the No. 1 recommended manure management option by agencies and industry professionals. Before fertilizers were readily available and popularized, farmers composted livestock manure and food scraps and spread the finished compost on pastures, crops, and gardens. Experts typically do not recommend spreading fresh manure because of the risk of spreading parasites, pathogens (disease-causing organisms), and weed seeds. Spreading compost is excellent for soil health and pasture productivity. You can apply a thin layer of compost to pastures, lawns, gardens, and crops during the growing season.

What if you don’t have enough pasture to apply compost? Or maybe composting isn’t your thing? In that case you might need to explore off-site options.

Horse Waste for Dairy Farms

You can investigate whether you have a local dairy farm or other livestock operation that will accept horse manure. Dairies are often willing to take horse stall waste that contains bedding, viewing it as a highly absorbent, free material they can reuse as bedding for dairy cows. Most parasites and pathogens found in spent bedding are species-specific, so those affecting horses typically do not affect ruminants.

Horse Manure Compost for Landscaping

Compost tends to be much easier to rehome than straight manure. Creating nicely composted stall waste doesn’t take much more effort than stockpiling manure. With a little advertising and an easy-to-access location, you might attract enough people to take all of it—composted or not—particularly in urban areas with avid gardeners or landscapers. If you can help others load it with a tractor and bucket, that also makes it more appealing. You can also spread the word to local flower and garden clubs, nurseries, and native plant clubs, or post on Craigslist, Facebook groups, or other social media platforms.

Hauling Horse Waste Off-Site

If you choose to haul your horses’ waste off-site, you can either hire someone to haul it for you or you can get the equipment to do it yourself. Some of these businesses might take it for free or charge a tipping fee. Paying to dispose of manure off-site might be the easiest way to go if you have a mountain of manure, lack of storage space, or don’t have the time to research or implement other options. These businesses often take horse manure:

• Compost or topsoil companies; 
• Nurseries and flower gardens;
• Tree farms;
• Crop farmers;
• Organic growers; and
• Flower gardeners.

Check with your local garbage hauler or shavings supplier because they might be able to haul off manure for a fee and take it to a composting facility or topsoil company. Some compost or topsoil facilities rent drop boxes they deliver and empty. They usually charge pickup, rental, and disposal fees.

Take-Home Message

Smart manure management on small horse farms often involves using a mix of strategies. From composting and reusing stall waste to connecting with gardeners, farmers, or haulers, the right combination depends on your space, time, and goals. With a little planning and creativity, you can turn manure into a useful resource rather than a problem.

Some of the biggest indicators of a horse’s health are his body condition, weight, and muscle development. So if you’re starting to see your horse’s ribs, or if he has a less-than-­desirable topline—the muscles that support the spine, neck, and ­hindquarters—then he might need to build weight or muscle. But what is the difference between adding weight and muscle? How do you know which your horse needs, or is he deficient in both? And, then, how can dietary changes help your horse bulk up?

Dietary Energy 101

It’s important to understand dietary energy and how it relates to a horse’s food sources. Basically, energy equals calories, which are measured in kilocalories. In horses, which need thousands of kilocalories per day, energy requirements are expressed as megacalories (Mcal).

There are various types of energy—gross energy (GE), digestible energy (DE), metabolizable energy (ME), and net energy (NE)—but, for the purposes of this article, we’ll focus on DE. This is the energy listed on feed labels and that nutritionists reference most. It’s the energy that can be digested from a feed after adjusting for the energy lost in fecal output. Because calculations within the equine nutrition industry vary, DE values of feedstuffs are considered estimates.

For energy, horses consume fat, carbohydrates, and protein. Fats are the most calorically dense feed, at 9.4 kcal/gram of GE (the heat produced when a feed is completely oxidized, or burned). Carbs offer 4.15 kcal/gram, and proteins 5.65 kcals/gram.

Carbohydrates (fiber, starches, and sugars) are the main components of forages. Horses require them for digestive health, to help buffer stomach acid, and as a good energy source.

Protein is the least-efficient energy source, says Russell Mueller, MS, PAS, a member of the Equine Research and Innovation Team at Cargill Animal Nutrition, in Minneapolis, Minnesota. Horses can expend more energy digesting protein than they gain from it, he says.

Now let’s think about how a veterinarian or nutritionist might recommend you add weight, muscle, or both to a horse. Note that if a horse is calorie-deficient, he will also be muscle-depleted. You cannot build muscle without adequate calories, says Clair Thunes, PhD, an independent equine nutritionist and owner of Summit Equine Nutrition, in Gilbert, Arizona.

Evaluating the Horse

The first thing to do is evaluate the horse to see where he falls on the Henneke body condition score (BCS) chart, says ­Mueller.

Ideally, the horse should score between a 4 and 6, meaning you can feel but not see his ribs. His withers, neck, and shoulders should be rounded, and the withers should have a layer of fat over them. The horse has a crease down the back, but it is not pronounced. The backbone, tailhead, and hip bones also have some fat cover.

If your horse is ribby (and a veterinarian has ruled out underlying health issues causing weight loss), he needs more calories in his diet, says Mueller. If the horse is angular over his topline (withers, back, loin, top of the hip, and croup region) and/or is sunken in around the neck, he needs to build muscle. Developing the topline is important because it plays a vital role in how a horse performs and handles when ridden. Adjusting the protein and amino acids in the diet can help.

Adding Calories for More Fat Cover

Each horse requires a minimum DE per day for maintenance (to stay the same weight). Different activity levels increase daily DE requirements. You can find these values in the National Research Council’s (NRC) 2007 Nutrient Requirements of Horses, although many horse owners simply consult their veterinarians or nutritionists about their horses’ nutritional needs. These experts can evaluate what nutrients each horse is taking in with his base diet to see if that diet is ­appropriate or needs to be changed.

For a horse to gain weight, it takes an increase of about 20 Mcals of DE above maintenance to gain 1 kilogram (2.2 pounds). However, this varies depending on grain composition and energy sources. To move up one score on the Henneke scale, says Thunes, a horse needs to gain 16-20 kilograms (35-44 pounds), but this varies depending on the horse’s weight. Assuming your horse needs 20 kilograms to move up the scale, he must consume a total of approximately 400 Mcals above maintenance needs.

Thunes presents two possible scenarios for adding more calories:

• You could feed the horse an additional 5 pounds of grass hay, which will provide about 4-4.5 Mcals per day. Therefore, it would take around 100 days for the horse to move up one BCS.
• You could feed the horse the minimum serving of a higher calorie feed, such as a senior or performance feed (about 6 pounds is a common minimum daily serving, says Thunes). Then it might only take 45 days to move up one BCS as the horse consumes around an additional 9 Mcals per day (this could differ based on individual feed formulation).

The NRC has created a table (see below) showing how much time it takes for a horse to go from 4 to 5 on the Henneke scale, based on how much additional DE he’s consuming above maintenance.

Forage Comes First

When changing a horse’s diet, Thunes takes a forage-first approach, which is the safest way to put on weight. Because ­alfalfa provides more calories per pound than grass hay, she says owners can switch up to 25% of their hay to alfalfa.

“If this does not do the trick, feeds using fiber sources like beet pulp and soybean hulls are a good option, as these are still fiber but higher in calories,” she says.

Mueller has found that owners are more willing to change their feed or their supplements than their forage, simply because of availability and/or growing conditions. “A more cost-effective route may be to spend a little more money on your hay versus spending a lot more money on feed, if you have another hay type or quality available to you,” he adds.

Mueller says he might suggest owners in regions where bermuda hay is ­prevalent switch to a cool-season grass hay (e.g., orchardgrass, bromegrass), which will provide more calories per pound.

Add Fat and Carbohydrates Next

If you can’t achieve weight gain with pasture or hay and other fiber sources alone, Thunes recommends adding something more calorically dense to the diet or substituting some of the forage with a new feed. “Concentrate feeds that are higher in fermentable fiber, fat, and/or starch are going to be more calorically dense than most hays,” she says.

Mueller always asks owners about their horses’ temperaments, because calories from a starch source can hype up a horse, which might not be desirable for an already-excitable animal. He adds that he might, however, use a higher starch- or sugar-based carbohydrate source of calories to add weight to a horse that does high-intensity bursts of speed in competition—roping, barrel racing, short-distance racehorses, etc.—because they need this type of energy source.

For more excitable horses, instead of starch Mueller adds a fat source such as oil. He prefers flaxseed or soy oil versus canola or corn oil because the latter two have poorer omega-3 to omega-6 ratios, which can increase inflammation in the horse’s body. When he wants to provide the essential omega-3 fatty acids docosahexaenoic acid and eicosapentaenoic acid, Mueller says fish oil has its benefits.   

When supplementing fat, a horse might hit a maximum intake threshold with liquid fat if he doesn’t like consuming a lot of fluid in his feed. Therefore, Mueller sometimes uses an extruded fat ­supplement. 

In addition, he might suggest a blend of fat and carbohydrate calories, because pure fat-based calories are pricey.

Developing Muscle

While muscle development happens bodywide in horses, it is easier to see and measure using the horse’s topline, says Mueller. To evaluate a horse’s muscle development, he uses a topline evaluation system that scores muscle quality along the topline from an A to a D. He says this system acts as a supplement to the Henneke body condition scoring system.

To add or develop muscle you must evaluate your horse’s current dietary protein levels and sources before increasing intake or changing protein sources. Mueller says he might opt to add a higher-protein feed or supplements or make a change in hay.

“Alfalfa is one of my protein levers,” he says. Alfalfa’s benefit is that it can up protein and add calories for a horse that needs both.

Crude protein requirements for horses vary. An adult horse at maintenance only requires 10% protein. Performance horses are often fed a product with 14% crude protein, while halter horses might get upward of 16%. Researchers have not determined a maximum amount of protein that can be fed.

When choosing a protein source, says Mueller, the amino acid profile is key because amino acids are protein’s building blocks. While horse owners might only see the crude protein content listed on a feed label, they can ask the manufacturer more about the amino acid profile.

Thousands of amino acids exist in nature, but only 20 have dietary benefits for horses. Ten of these are essential amino acids, meaning the horse can’t make them and, thus, must consume them in his diet.

“The ratio of these amino acids and the amount of those amino acids are what determine your protein quality,” Mueller says. “You need to focus on the quantity and quality of the amino acids. Are you getting enough, and are you getting the right amounts of specific amino acids that will truly bring about the best muscle development in the horse?”

A limiting amino acid is an essential amino acid that sometimes doesn’t appear in adequate amounts in a feed. A horse cannot synthesize adequate protein if he doesn’t consume enough limiting amino acid. New protein will only be synthesized to the amount of the limiting amino acids. If the horse runs out of limiting amino acids, he can’t make use of the other amino acids he has consumed.

Lysine is the only amino acid that has a specific listed requirement in the NRC guidelines. For a 500-kilogram (1,100-pound) adult horse at maintenance, NRC recommends 27 grams of lysine per day, but this amount changes based on the horse’s age and use. For instance, a lactating mare in the first month after foaling needs 85 grams of lysine per day.

Soybean meal and other seed meals are great lysine sources, says Mueller, and show up in many feed ingredient lists.

Thunes says whey protein that provides the branched-chain amino acids, especially leucine, will help support muscle development, as well.

For some horses Mueller might recommend a diet ration balancer with high protein or purified amino acid supplements. He says the issue with supplements, however, is the lack of research behind them, so much of the information he has gathered is from field observations.

Take-Home Message

When a horse needs added bulk, in fat or muscle or both, it’s crucial you make the right changes to supply the necessary dietary components to see improvements. When in doubt, an equine nutritionist or your veterinarian can help guide you through these changes. This can help eliminate expensive and unrewarding blind guesses and trial and error.

Q: Can a nutritional imbalance or food allergy cause hives? My gelding broke out into hives after I started feeding him pure alfalfa hay, but when I switched him to Timothy grass hay the hives disappeared.

A: Owners often attribute itchy skin, hives, loose manure, and even behavioral changes as potentially being the result of food allergies, and they commonly presume alfalfa is the culprit. Whether these reactions are truly allergies—specifically food allergies—is often a point of debate. A food allergy is defined as an immune-mediated adverse reaction to food, where the body is reacting to a protein within that food or other substance, such as pollen. Allergies are reactions to substances that would not normally be problematic for most individuals.

Food allergies in horses do exist; however, most researcher and veterinarians consider them rare. If a horse has hives because of a food allergy, they would be expected to be all over the body rather than in isolated areas, which would point more toward a contact allergy from something like laundry detergent. The reaction might manifest as itchy hives or be solely in the gastrointestinal tract and result in clinical signs such as diarrhea.

Owners and veterinarians often reach for blood tests to diagnose allergies. These panels often include foods such as hays and common feed ingredients; however, research has shown that these tests are frequently inaccurate. The only true way to diagnose a food allergy is to do a withdrawal diet and then reintroduce the specific ingredients you believe the horse is allergic to. This takes time (often eight to 12 weeks) and dedication, and most owners are not willing to reintroduce ingredients that might be allergens, especially if the horse’s symptoms have resolved.

Horses can also have food intolerances or sensitivities, which are not immune-mediated reactions. They tend to present as loose manure and changes in behavior rather than hives, but hives could be present. Sensitivities might have a threshold such that the horse can handle the feed until consumed at a certain level. This is similar to lactose intolerance in people, where affect individuals might be able to consume small amounts of lactose in ice cream, but if they also eat a cheese pizza at the same meal, they show symptoms of their intolerance.

It is possible that your horse is not truly allergic to alfalfa and could handle alfalfa fed in smaller amounts, but a solely alfalfa hay diet causes issues for him. The only way to know whether that’s the case would be to add some amount of alfalfa back into the ration with the Timothy hay and see whether the hives return. This sensitivity threshold is likely why many horses can cope with supposed problem ingredients when they are in relatively small amounts such as in supplements but cannot cope with them when fed in greater quantities.

Another component of managing allergies is horses with allergies tend to be allergic to multiple things, such as insect bites and certain pollens. If you can control even a few of the allergens the horse is exposed to, you might eliminate or reduce allergic symptoms. So, if you can remove certain allergens that are easier to control from the horse’s environment, the horse might be able to handle exposure to other allergens, such as feed ingredients, without issue.

Q: I am considering producing hay for at least my own horses within the next few years. I’ve heard of sustainable hay production, but I don’t know much about it. What is it, and what do I need to get started?

A: Sustainable hay production refers to practices that protect the environment while producing a high-quality hay crop, says Sandy Young, owner of Treasure Valley Hay, in Nampa, Idaho. Young has been a hay broker since 2008, focusing primarily on providing high-quality hay for horse owners in Southwestern Idaho, but she has customers in all Western states.

“Growers want to produce a high-quality product and feed the world … as well as (understand) what they need to produce it,” says Young. When she evaluates a potential hay grower before agreeing to broker their hay, she looks for “good quality, good color, and fresh smell without mold or foreign objects.”

She also considers the grower’s farming practices. “Is their hay produced as organically as possible, without chemicals?” she says. “If a grower is spraying, what are they using?”

Sustainable grass hay production usually involves growing a variety of plant species in the same field. “It often includes rotating crops, such as with teff hay, which will help maintain soil health,” says Young. “Using integrated pest management strategies (a science-based approach combining different pet control tools) will help reduce chemical use.

“Promoting biodiversity and long-term soil health are all part of regenerative agriculture, the new buzzword these days,” Young adds. This means the grower employs techniques such as planting cover crops, reducing or eliminating tillage (plowing), which disrupts the soil’s ecosystem, and avoiding bare, exposed soil that’s prone to erosion from wind or rain. It also involves using organic fertilizers and trace minerals, and reducing or eliminating chemical inputs to support soil microbes and improve soil structure and fertility, she adds. These practices help the soil retain moisture, which reduces polluted runoff and dust storms.

“Healthy, living soils help plants grow longer, stronger root systems, which in turn allow plants to better utilize minerals and nutrients in the soil,” says Young. “It’s becoming so obvious that soils are deficient from decades of modern farming practices that have depleted our soils of microbes and nutrients.”

Healthy soils are a balance of organic matter, trace minerals, soil life, and the plants grown.

Take-Home Message

Sustainable hay production involves protecting the environment while producing a high-quality hay crop. This can include producing forage as organically as possible, with minimal chemicals and a focus on the long-term health of balanced soils. “Sourcing sustainably grown hay is protecting the environment,” says Young.

Q: I’ve always enjoyed giving my horse a warm bran mash in cold weather, but this doesn’t seem to be something people do much anymore. Is there still a place for wheat bran in my feed room?

A: Growing up I routinely fed a warm bran mash to my horse in the winter, especially on days when he worked hard. However it’s far more unusual now in part because we’ve realized that it might not be as beneficial as we once believed.

In my 1983 8^th Edition of the British Horse Society and The Pony Club Manual of Horsemanship it states that a bran mash is a “very useful warm food after hard exercise and hunting.” It goes on to say that after adding boiling water to the bran, you should add a generous amount of salt along with some oats, and then feed once cool. It finishes by saying “bran mash has a laxative value, and it has everything to recommend it when fed once a week to horses in work and to invalid horses. It is also a convenient way to administer medicines such as worming compounds.”

So how did a feed and feeding practice that were once so popular fall out of favor? To better understand that you need to understand your horse’s digestive tract, as well as the composition of the feed.

About Diet Changes and Digestive Tract Upset

Most of us are well aware that changes to a horse’s diet should be made gradually over several days. The reason for this is that the digestive enzymes, the amount secreted as well as the bacteria in the horse’s hind gut, are somewhat specific to the diet being fed. Therefore, if you change the makeup of the diet the enzymes and digestive bacteria must adapt, and this takes time. In the meantime if too much new feed is fed the horse might not be able to fully digest it and can lead to digestive disturbance (e.g., diarrhea, gas, and colic, etc.).

As previously mentioned, horse people used to routinely feed bran mashes once a week, largely for their believed laxative effect. Since becoming more educated in equine nutrition, it’s fascinated me that—while we take great care not to suddenly change a horse’s diet when starting most new feeds—this logic goes out the window when it comes to a bran mash. Essentially, when you feed a bran mash once a week you’re breaking all the guidelines you typically follow in keeping your horse’s diet consistent. The “laxative effect” might be because the feed change is causing digestive distress! This is probably not the best method of ensuring your horse’s digestive contents stay on the move.

Wheat Bran’s Nutritional Imbalance

Wheat bran has also fallen out of favor because of its high phosphorus level. In fact wheat bran has an inverted calcium to phosphorus ratio, meaning that it contains more phosphorus than calcium. This is actually common in traditional grains such as wheat, oats, and barley. However, wheat bran is particularly high with a phosphorus content of about 1% and calcium at only 0.15%.

Researchers realized feeding diets with a lot of wheat bran increased the risk of developing secondary hyperparathyroidism, a condition that results from a calcium imbalance potentially caused by horses consuming a diet too high in phosphorus. “Big head” or “bran disease” was far more common when horse owners and managers fed traditional grains and wheat bran more commonly than we do today. In reality this condition is unlikely to result from feeding a bran mash once a week. It’s far more likely if bran or traditional grains are fed daily in a poorly balanced ration. Traditionally any number of unfortified grains could have caused a similar issue, but because, proportionally, brans add much more phosphorus per pound than the grains, they are often considered a larger problem. With the concern over big head and potential links to bran, much less wheat bran is now fed and most rice brans are fortified with additional calcium carbonate to neutralize the problem.

So, What’s Right About Bran?

Going back to the quote from my Manual of Horsemanship, if a bran mash has “everything to recommend it,” what’s it doing right, given the two already discussed areas of concern? First, the manual hints that bran mashes are generally welcomed by even the most picky eater. Often, after very long and heavy work such as fox hunting, horses might have a reduced appetite and the goal is to get the horse eating and the digestive tract moving. Some sick horses that have gone off feed can be tempted to eat with a bran mash. Therefore, a bran mash can be a very useful tool when faced with a horse that has gone off feed and will not eat anything else.

Second, adding salt to a bran mash is a great practice, especially when fed after work that might have incurred heavy sweat losses.

Alternative Warm Mashes for Your Horse

So, when you want to give a bran mash is there something else that might be more beneficial? Is there a better way?

If you already give your horse supplemental feed, whether it is pellets or a textured feed, add hot water to make a warm mash just as you would with wheat bran. This way you are creating the mash but using familiar feeds that are less likely to irritate the gastrointestinal tract.

If you only feed forage, purchase some hay pellets that are like the forage you feed and use them to make a mash.

Next add some salt, or if you already give salt every day and your horse has been sweating heavily, add an electrolyte. If you need to entice a picky eater or a horse that has gone off feed, try adding carrot or apple peelings. If you have your heart set on a weekly bran mash, then I suggest adding a small amount of bran to your horse’s every day feed so that the mash is not a novel feed to your horse’ digestive tract. But be careful to keep the amount of bran small and consider discussing with an equine nutritionist how to add bran to your ration while maintaining a balanced mineral profile.

Q. I feed my ulcer-prone horse alfalfa before riding, because I’ve heard the calcium in alfalfa works like a big Tums antacid to keep my horse’s stomach from hurting during exercise. I was recently told that alfalfa pellets don’t work and that I should use alfalfa hay or chop instead, because the alfalfa needs to create a “hay mat” in the stomach to keep acid from splashing up into a horse’s esophagus (basically, causing horse heartburn). Is it true that I need to feed alfalfa hay or chop instead of pellets?

A. You are correct. Alfalfa is typically high in calcium, which researchers have shown reduces stomach acidity due to its buffering capacity. In a study at Texas A&M University, 12 horses were assigned to one of two groups: a 1:1 ratio by weight of Bermuda hay and a concentrate feed or of alfalfa hay and the same concentrate feed.

Treatment periods lasted 28 days before horses switched to the other diet with a 21-day washout period between treatments. At the start of the study each horse went through a gastroscopy to determine whether they had gastric ulcers and, if so, their severity. Horses were rescoped after the 28-day treatment periods to determine whether any existing ulcers had improved or worsened or new ulcers had appeared.

The researchers found that ulcer severity scores were significantly lower when horses ate alfalfa hay compared to Bermuda hay. Feeding alfalfa prevented ulcer formation in 11 of 12 horses that did not have ulcers initially, whereas only three of the 12 horses that did not have ulcers stayed ulcer-free when fed Bermuda. The team attributed these results to alfalfa’s higher calcium and protein content providing greater buffering capacity. The complex carbohydrate fractions found in alfalfa’s cell walls have also been shown to provide better buffering than those found in grass hays.

It’s clear that alfalfa does a good job of buffering the acid in the equine stomach. The question therefore becomes, does it matter what form the alfalfa is in? Long-stem hay requires a good amount of chewing before being swallowed, and chewing results in saliva. Equine saliva contains a good amount of sodium bicarbonate, which will also buffer stomach acid. Pellets take less chewing so result in less saliva and lower buffering from the bicarbonate. So long-stem hay would be preferable from that perspective. But what about the fiber mat?

The equine stomach is not completely full of acid. Large feed particles float on top of the acid, helping prevent it from splashing into the upper portion of the stomach where most ulcers occur. Pellets have a much smaller particle size than long-stem fiber, so alfalfa hay is more likely to make a better mat than pellets. Keep in mind that any forage in hay form—not just alfalfa—will form a good mat and cause saliva production. So if your horse has eaten hay within the few hours prior to your ride, he likely already has a good mat.

The calcium in pellets might buffer more quickly than hay due to the smaller particle size, but the smaller particles might also cause the calcium to move out of the stomach faster than larger particles would. So the question becomes: Which is more important, the hay mat or the buffering? If the stomach’s acidity is low, it won’t matter as much if the acid splashes into the stomach’s unprotected upper region. A hay mat is less important when the stomach acid is less acidic, and depending on when your horse last ate hay, a mat might already exist.

If you’re arriving to ride your horse and he has an empty stomach, and you give him alfalfa while you’re grooming, he might not have time to consume much alfalfa hay, because it requires more chewing. You might get greater buffering capacity more quickly by feeding pellets, although you won’t get a great mat. Most stomach buffers are relatively short-lived, lasting at most a couple of hours. Research has shown that some commercial buffers on the market buffer effectively and more quickly than alfalfa. These can be great options when given before exercise, if you need buffering capacity quickly.

Alfalfa’s ability to help reduce ulcers, and in which form you should use it, depends on a combination of complex interactions. The best solution for each horse might not be completely clear, but what we do know is that giving some form of alfalfa before riding a horse with an empty stomach will likely have a positive impact and could reduce your horse’s risk of developing gastric ulcers.

Equine metabolic syndrome (EMS) is a complex condition that involves insulin dysregulation (ID), obesity, and an increased risk of laminitis. Horses with EMS often need a multifaceted management approach to improve their quality of life and prevent serious complications. These five key management changes can help you improve your EMS horse’s metabolic status and overall well-being.

1. Optimize Diet and Forage Selection for EMS Horses

Diet plays a crucial role in managing horses with EMS. “Diets high in nonstructural carbohydrates are a risk factor for development of insulin dysregulation, a key component of EMS,” says Katie Wilson, DVM, Dipl. ACVIM-LAIM, clinical associate professor of large animal internal medicine at the Virginia-Maryland College of Veterinary Medicine, in Blacksburg, Virginia.

“One of the simplest and biggest changes owners can make is actually weighing the amount of concentrate and forage their horses are eating per day to better control caloric intake,” says Wilson. Grass hay with an NSC content of less than 10% is ideal for horses with metabolic problems, she adds. If the NSC content is unknown or higher than 10%, soaking the hay for at least 60 minutes (and discarding the soak water) before feeding can make it safer for EMS horses.

Avoid feeding your EMS horse concentrates unless absolutely necessary, Wilson says. However, forage-only diets do not provide all the vitamins and minerals (i.e., sodium, chloride, copper, zinc, Vitamin E, and selenium in areas with selenium-deficient soil) horses require, so they need a ration balancer if the diet is forage-based, she adds. “Some ration balancers are high in NSC, however, and can induce an exaggerated insulin response after feeding, so ingredients or individual horse response to feeding should be evaluated.”

2. Implement an Effective Exercise Routine

Exercise also plays a crucial role in managing EMS. An effective exercise routine can help horses safely lose weight (if needed) and improves insulin sensitivity. Always work with your veterinarian when creating an exercise plan for horses with a history of laminitis to avoid exacerbating the condition or unknowingly cause pain, says Wilson. Horses recovering from laminitis should only exercise after veterinary clearance.

After a laminitic episode and once cleared, Wilson recommends gradually introducing physical activity, such as five minutes of walking followed by 15 minutes of trotting, repeated five times per week. For EMS horses without laminitis, moderate exercise, such as trotting and cantering for at least 30 minutes, five times per week can benefit their insulin sensitivity.

3. Monitor EMS Horses’ Body Condition and Weight Regularly

Horses with EMS often display generalized or regional adiposity, but even horses with a normal body condition can have ID, says Wilson. Regularly assess your horse’s body condition to ensure he remains a healthy weight. “Assessing body condition score every two weeks can help to quantify changes that might not be noticed,” she explains. “Assessing body weight can be helpful as well, by either using an equine scale if one is accessible, or a weight tape.”

“Reducing body condition (if warranted) has been shown to improve insulin sensitivity, and weight reduction can help decrease the forces in the foot that result in sinking or rotation in horses with laminitis,” adds Wilson.

4. Adjust Turnout and Grazing Practices for EMS Horses

Unrestricted grazing can harm EMS horses because pasture often contains high levels of sugars and NSCs. “Free-choice grazing should be restricted in horses with EMS and (a history of or active) laminitis,” says Wilson. She suggests turning affected horses out in a dry lot or small paddock with little to no grass or using a grazing muzzle or strip grazing to limit pasture access.

“If horses need to be reintroduced to grazing after laminitis has resolved, it should be done slowly and blood insulin concentrations should be measured regularly to assess the horse’s insulin response to the added carbohydrate content of the grass,” says Wilson.

5. Work Closely With a Veterinarian

Equine metabolic syndrome involves many changing factors, so work closely and regularly with your veterinarian to ensure effective management. “One common mistake is assuming that a one-time change in management or feeding practices will fix the problem,” says Wilson.

Regular examinations and blood insulin monitoring can help your veterinarian tailor management strategies to the horse’s specific needs. Your vet needs to assess your horse’s insulin levels after dietary changes or modifications to his grazing schedule and at different times of year because season can impact insulin sensitivity, adds Wilson.

Equine practitioners also play a crucial role in helping horse owners navigate logistical challenges and develop practical, individualized management plans. “Veterinarians understand that there are usually many logistical limitations to implementing the ideal changes recommended for a horse with EMS and are happy to work within the owner’s restrictions to develop a plan that will work best for an individual horse,” says Wilson.

Take-Home Message

Managing a horse with EMS takes a proactive, tailored approach that fits the horse’s specific needs. By making key changes to diet, exercise, body condition monitoring, and turnout strategies—while increasing veterinary collaboration—owners can significantly improve their EMS horses’ health and well-being. Equine metabolic syndrome has no cure, but consistent monitoring and adjustments can go a long way in preventing laminitis.

Q: How can I prevent nutritional deficiencies without causing developmental issues in a growing foal?

A: Developmental orthopedic disease (DOD) is a common concern in young horses, referring to a group of conditions where skeletal growth occurs abnormally. While nutritional mismanagement can be a factor, proper nutrition can help manage the risk of developmental issues.

Feeding young horses requires careful planning, starting before birth. Ensuring the mare’s optimal nutrition during pregnancy and lactation is essential for fetal development and milk quality. Once born, foals should begin consuming concentrates at around 28 days old; a good rule of thumb is 1 pound of feed per month of age per day. Feeding with progressive and consistent increases will encourage steady growth curves associated with optimal skeletal development. Erratic changes, feeding an improper concentrate, offering it free-choice, or making sudden changes to the amount of concentrate, can result in the unpredictable growth curves that are the hallmarks of DOD development. You can design your feeding program to support rapid versus moderate versus slow growth rates depending on the goals for that foal, but make these decisions with few changes occurring during the early growth period.

It’s a misconception that excess calories or protein alone causes DOD. Instead, imbalances in these and other nutrients have been linked to abnormal growth. Think of calories as the fuel for growth and nutrients (amino acids, vitamins, and minerals) as the structural building blocks. Too much fuel and too few building blocks will create rapid, incorrect growth. Too little fuel and you will be missing out on some genetic potential for growth, which could hinder muscle development. In addition to energy and protein, other nutrients need to be maintained in certain ratios to ensure optimal utilization. Calcium and phosphorus are classic examples of nutrients that should remain balanced to a ratio of no less than 1:1 (2:1 being optimal). Similarly, zinc and copper must be balanced in a ratio of around 4:1 in a complete diet. 

A simple way to stay on track is to:

1. Feed to suitable body condition, which is when ribs are not or just barely seen and easily felt, and
2. Use only feeds appropriate for growth. Look for items designated for mare and foal, growth, or all life stages. This means the nutrients are balanced for young horses, and the balance between calories and nutrients is appropriate. 

The key difference between growth and performance feed is that a performance feed for an adult horse has a higher ratio of calories to nutrients, meant to support working horses but not adding structural growth. Growth feeds are available at all calorie levels, so the exact choice of concentrate will be dictated by the individual’s metabolism and forage intake and quality. Ration-balancing feeds are a good option to provide nutrients if your horse receives sufficient calories from forage alone. A young horse should generally stay on a growth-appropriate program until 2 years old, sometimes longer for particularly late-maturing breeds such as some warmblood or draft breeds.

Do you have an equine nutrition question?

What does it take to optimize the equine immune response and fight off disease?

Could your horse’s diet, workload, and environment undermine his immune system, leaving him vulnerable to infectious diseases, allergies, and delayed healing? Very much so, experts say. “Horses are susceptible to various stressors that can compromise immune function over time,” says Samuel White, PhD, associate professor and head of projects at York St. John University, in England. With expertise in applied immunology, White has studied culprits of equine immunosuppression. So far, excessive exercise, poor nutrition, chronic stress, and prolonged environmental exposure have made the list.

In this article White, along with an internal medicine specialist and an equine nutrition consultant, demonstrates the complex connection between a horse’s immune health, environment, and lifestyle.

Blank Slate: Equine Immunity at Birth

Unlike humans, who come into the world protected by antibodies acquired in utero, foals develop inside multilayered epitheliochorial placentas that only allow minimal maternal transfer of antibodies to the fetus. This lack of immunity transfer during pregnancy makes newborn foals’ immune systems naive (vulnerable) at birth.

“Equine neonates depend on their dams’ antibody-rich colostrum for early protection against infectious agents,” says Allen Page, DVM, PhD, assistant professor in the Department of Veterinary Science at the University of Kentucky’s Maxwell H. Gluck Equine Research Center, in Lexington. Fortunately, beyond the initial reliance on colostrum, this lack of immunity at birth doesn’t appear to put equids at a disadvantage later in life, and Page hasn’t come across any long-term effects from this early vulnerability.

Immunity Through Vaccination

Another key characteristic of the equine immune system is a shorter and less robust immune response to vaccines compared to humans, says Jeremy Frederick, DVM, Dipl. ACVIM, owner of Advanced Equine of the Hudson Valley, an ambulatory equine veterinary practice based in Wappingers, New York. These factors explain why horses need annual or biannual boosters, whereas people can maintain adequate immunity against a particular disease for a decade or more post-vaccination. “Horses generally have lower levels of memory cells that produce long-lasting … lymphocytes (white blood cells that produce antibodies to fight infection), which means immunity from vaccines wanes faster, necessitating more frequent boosters,” Frederick says. “This is particularly true for respiratory viruses (influenza and equine herpesvirus, aka EHV) and mosquito-borne encephalitis viruses (mainly EEE and WEE).”

He also explains that horses encounter more infectious agents than humans, particularly those from other animals, insects, and the environment. This contributes to their need for more frequent vaccinations. “This effect is compounded when horses regularly travel to events, shows, or new environments where they interact with unfamiliar animals and environments,” Frederick adds.

So, how can you maximize the protective effects of your horse’s vaccines? “Firstly, cover your bases by working with your veterinarian to ensure your animals are on a proper vaccination schedule,” Frederick says. The American Association of Equine Practitioners (AAEP) provides a list of core vaccinations that every U.S.-based horse should receive at least annually and additional risk-based vaccines depending on exposure risk.

Some horse owners have their veterinarians draw blood to check antibody titers before (or instead of, depending on results) administering annual boosters. “However, since this is an added expense and there are no established protective levels for most diseases, few clients choose to check titers regularly,” Frederick says. “Therefore, annual or biannual vaccinations are recommended for most horses.”

A Dusty Living Environment

“The barn environment plays an important role in immune health,” says White. Most stabled horses eat, sleep, and live on dusty, ammonia-laden shavings, with brooms (or worse—leaf blowers) stirring
up additional dust and other harmful respiratory triggers. “Good ventilation and low-dust bedding reduce respiratory irritants and help maintain respiratory health,” White says. “Ensuring feed and bedding are clean and stored properly minimizes exposure to harmful spores and bacteria, limiting immune stress.”

Don’t Overlook Nutrition

Nutritional deficiencies can harm horses’ overall health, including the immune system. “A diet lacking in vitamins, minerals, or antioxidants can absolutely weaken the immune system, making horses more vulnerable to infections,” says White. “Horses with poor or unbalanced nutrition may also experience a compromised gut microbiome.”

In recent years scientists established a direct link between gut microbiome health—that of the community of microbes living in the cecum and large intestine—and systemic immunity¹. “A healthy microbiome aids nutrient absorption and reinforces the gut’s barrier, reducing inflammation and leakage and strengthening systemic defenses,” White says. “Essential nutrients, including vitamin E, selenium, zinc, and copper, are integral to immune function at the cellular level. They allow immune cells to function properly.”

How can you support your horse’s microbiome and immune health through nutrition? Ofelia Del Principe, certified independent equine nutrition consultant and the owner of Whitfield Equine Nutrition LLC, in High Falls, New York, says the answer begins with the basics. “Supporting equine immune function starts with feeding a balanced diet built on a foundation of forage that meets all of the individual’s nutrient requirements,” she says.

“If we need to further support a horse’s immune system, we can look into supplementation,” Del Principe adds. “Supplementing with the antioxidants vitamin C and vitamin E, omega-3 fatty acids, yeast, and/or certain fibers may improve immune function, but I always give a caveat: Even the most judiciously selected supplements will do little to nothing if the horse is not already eating a balanced diet,” she says.

Stress and the Immune System

In people glucocorticoids (GCs), notably the stress hormone cortisol, are widely recognized for suppressing the immune system². “Chronic stress is a major contributor to immunosuppression in horses as well,” says White. “Horses are sensitive to environmental changes, transport³, and social disruptions within the herd, all of which can increase cortisol levels and reduce immune resilience. As such, chronic stress has been shown to impair immune responses, making horses more susceptible to infections or triggering latent viruses (to become active).” Equine herpesvirus is a prime example of this phenomenon.

Fortunately, just like nutrition, horse owners can influence stress. “Minimizing stress through consistent routines, stable herd dynamics, and controlled exposure to new situations can limit immunosuppression,” explains White. “Furthermore, reducing exposure to environmental allergens, particularly for horses prone to conditions like asthma and insect bite hypersensitivity (IBH), can lessen immune strain and prevent unnecessary immune activation.”

How Exercise-Induced Stress Impacts the Horse

The body keeps the score, and stress from physical exertion counts toward that tally. “Regular exercise is beneficial for overall health, but overtraining of performance horses can elevate cortisol levels and reduce lymphocyte counts. Horses subjected to continuous high-intensity training often experience slower recovery times and higher incidences of respiratory infections, highlighting the importance of balanced exercise with adequate rest,” explains White.

Overtraining syndrome (OTS) caused by excess training and the lack of proper recovery can lead to temporary immunosuppression in equine athletes, say scientists who in a 2023 study found detrimental effects of OTS on the immune system in racing-bred Quarter Horses⁴. In another study, researchers found the immunophysiological responses of horses after exercise were breed-dependent to some extent. The authors found Thoroughbreds are less sensitive to exercise-induced stress than Korea’s native stocky Jeju breed, for example⁵.

Immunosenescence

“Aging negatively affects the immune system in what is called immunosenescence,” explains Page. In aging horses immunosenescence manifests as weakening immunity, leading to a reduced antibody response to vaccination. “This can be seen as the immune system having trouble responding to a new infectious pathogen (disease-causing organism) and/or vaccines while the ability of some immune cells to proliferate decreases,” he says, an explanation supported by recent literature⁶.

Immunosuppression from Drugs

“Immunosuppressive treatments like corticosteroids, while effective in controlling inflammation and allergic symptoms, can increase a horse’s vulnerability to infections by broadly suppressing immune function,” warns White. “These medications reduce immune cell activity, leaving the body less capable of fighting pathogens.” Long-term or high-dose use of steroids can lead to an increased risk of infections and, in certain metabolically prone horses, the debilitating hoof disease laminitis.

As for the cost-benefit analysis of corticosteroids relative to immune function, “the commonly used drugs dexamethasone and prednisolone can indeed make horses more vulnerable to infections and diseases,” says Frederick. “But this is a dose-dependent effect, so at lower doses typically used in conditions like allergies, the risk is low. However, at higher doses, we can see a reduced ability to fight off pathogens like bacteria, viruses, fungi, and internal parasites.”

Frederick recommends working with your veterinarian to reach the lowest effective dose of corticosteroids. White agrees. “Long-term, a comprehensive approach focusing on preventive care, nutrition, and environmental management is essential for protecting these horses and reducing the need for prolonged high-dose immunosuppressive drugs,” he says.

Take-Home Message

“Horses require more frequent vaccination than humans due to several factors related to their immune system, lifestyle, and environmental exposure,” says Frederick. Beyond following veterinary vaccination recommendations, “horse owners can mitigate threats to their animals’ immune health through appropriate exercise, balanced nutrition, stress reduction, and environmental control,” White adds. “Providing a stable foundation for immune health ultimately helps horses resist disease and recover more effectively when challenges arise.”

References

1. Kauter A, Epping L, Semmler T, et al. The gut microbiome of horses: current research on equine enteral microbiota and future perspectives. Anim Microbiome. 2019;1(1):14.

2. Yeager MP, Guyre CA, Sites BD, Collins JE, Pioli PA, Guyre PM. The Stress Hormone Cortisol Enhances Interferon-υ–Mediated Proinflammatory Responses of Human Immune Cells. Anesth Analg. 2018;127(2):556–563.

3. Miller AB, Harris PA, Barker VD, Adams, AA. Short-term transport stress and supplementation alter immune function in aged horses. PLoS ONE. 2021;16(8):e0254139.

4. Wilson J, De Donato M, Appelbaum B, Garcia CT, Peters S. Differential Expression of Innate and Adaptive Immune Genes during Acute Physical Exercise in American Quarter Horses. Animals. 2023;13(2):308.

5. Khummuang S, Lee HG, Joo SS, Park JW, Choi JY, Oh JH, Kim KH, Youn HH, Kim M, Cho BW. Comparison for immunophysiological responses of Jeju and Thoroughbred horses after exercise. Asian-Australas J Anim Sci. 2020;33(3):424–435.

6. DeNotta S, McFarlane D. Immunosenescence and inflammaging in the aged horse. Immun Ageing. 2023;20(1):2.

7. Birras J, White SJ, Jonsdottir S, Novotny EN, Ziegler A, Wilson AD, Frey R, Torsteinsdottir S, Alcocer M, Marti E. First clinical expression of equine insect bite hypersensitivity is associated with co-sensitization to multiple Culicoides allergens. PLoS ONE. 2021;16(11):e0257819. 

This article is from the Spring 2025 issue of The Horse: Your Guide to Equine Health Care. We at The Horse work to provide you with the latest and most reliable news and information on equine health, care, management, and welfare through our magazine and TheHorse.com. Your subscription helps The Horse continue to offer this vital resource to horse owners of all breeds, disciplines, and experience levels. To access current issues included in your subscription, please sign in to the Apple or Google apps OR click here for the desktop version.

Q: My horse has recently been diagnosed with EOTRH and needs some teeth removed. What can I do to support him nutritionally through this process?

A: Dental health problems in horses can be stressful to manage, but working closely with your veterinarian for medical care and considering how to support your horse nutritionally is a great start. Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a progressive and painful dental condition that primarily affects the tooth roots and surrounding gingiva (gums) in older horses. While the exact cause of this condition remains unknown, multiple factors likely contribute to its development.  

The treatment for EOTRH depends on the stage of disease. For mild cases your veterinarian might recommend more frequent dental examinations, pain management medications, or dietary modifications. As the disease progresses, surgical removal of teeth (typically incisors) and affected tissues might be necessary.  

When a horse has dental issues, evaluate his diet to ensure he can comfortably consume his feed and water. Make sure his roughage requirements are met and that he doesn’t have extended fasting periods.  

Adequate Roughage Intake for EOTRH Horses 

Horses have evolved to consume a fibrous diet with small frequent meals throughout the day. The severity of EOTRH and the number of teeth removed will determine what the horse can comfortably consume.  

A horse’s diet should contain a minimum of 1.5% of his body weight in forage daily. Whenever possible keep a portion of the horse’s diet as long-stem fiber to promote gastrointestinal health.  

Even after the removal of some teeth, horses often return to eating hay. Most can use their lips to eat grass and can grind forages with the molars. When they horse is not able to comfortably consume and chew the long-stem fiber, you need to introduce processed fiber sources . This could be chopped hay, hay cubes, beet pulp, or a complete feed. 

Nutritional Management Before and After Equine Dental Surgery  

When you schedule your horse’s dental surgery, it can be beneficial to add a fiber source that will be easy for your horse to chew. Make feed changes slowly. If your horse currently consumes hay but will be on mashes during his surgical recovery period, add some of those mashes into his program before surgery. This ensures the mash choice is palatable for your horse and his gastrointestinal tract has time to adapt to the changes.  

For example, if a 500 kilogram (1,100 pound) horse consumes 2% of his body weight in hay daily (10 kg or 22 lb), gradually introducing 1-2 kg (2-4 lb) of soaked hay cube mashes before dental surgery can help him adjust. Your dental surgeon can provide more detailed recovery instructions.  

Managing Severe Cases of EOTRH 

In severe cases where the horse can no longer consume hay and pasture is unavailable, designing a safe nutrition program can be challenging. In these cases use a combination of chopped fiber sources and complete feeds, which should be soaked and fed at a rate of 1.5-2% of the horse’s body weight per day (e.g., 16-22 lb for a 1,100 lb horse). 

To maintain digestive health and prevent long fasting periods, divide the daily feed amount into four to six small meals spaced no more than four to five hours apart. Soaking the feed reduces the risk of choke and encourages water intake. Prepare soaked feeds just before feeding to prevent them sitting for long periods of time and potentially going bad or becoming less palatable.  

Other Key Considerations for Horses With EOTRH 

Beyond feed amount and frequency, consider water temperature for soaked feeds and your horse’s feed preferences. Very cold water can cause discomfort to animals with dental issues and, because most of these horses are seniors, keep in mind their nutritional needs and feed preferences could change as they age.   

Outside of nutritional management, know your horse’s normal body condition score and recheck it to make sure he isn’t losing condition. Recognize when something is wrong so you can promptly contact your veterinarian. 

Long-term management decisions for horses that have had EOTRH will depend on whether the horse can go back to eating long-stem fiber. When the disease progresses to a point in which the horse can’t consume hay or even chew chopped forages, you might need to switch him to a complete feed that can be fed in many small meals daily. Consult a qualified equine nutritionist if you have questions about optimizing your horse’s nutritional management through dental health challenges.  

Do you have an equine nutrition question?

Until recently, equine researchers knew little about how dopamine regulates insulin secretion in horses. In two recent studies scientists examined this connection, with implications for managing conditions such as pituitary pars intermedia dysfunction (PPID, formerly called equine Cushing’s disease) and insulin dysregulation (ID).

“A significant number of horses and ponies with PPID produce very large amounts of insulin in response to dietary nonstructural carbohydrates (starches, sugars, and fructans), and this puts them at increased risk of laminitis,” said Simon Bailey, BVMS, PhD, FHEA, Dipl. ECVPT, FRCVS, professor of veterinary biosciences at The University of Melbourne’s Veterinary School, in Victoria, Australia.

Bailey and a research team funded by the Australian Research Council, the Waltham Petcare Science Institute, and Boehringer Ingelheim Vetmedica, including PhD candidate Nicolas Galinelli, have been working to identify the link between PPID and insulin production so they can find ways to better reduce the risk of laminitis in and manage these horses.

Dopamine’s Role in Equine Insulin Response

“Horses and ponies with PPID have reduced dopamine production in the brain (which causes the production of certain hormones from the pituitary gland to get out of control), and we have recently found that it is decreased in the bloodstream as well,” said Bailey.

To investigate the link between dopamine depletion and insulin metabolism in horses, the researchers administered alpha-methyl-para-tyrosine (AMPT), a modified amino acid that inhibits dopamine production, to six healthy Standardbred horses in a placebo-controlled crossover study. Bailey and his colleagues aimed to determine how short-term dopamine reduction affects insulin sensitivity and postprandial (post-meal) insulin responses.

In healthy horses, insulin—a hormone produced by the pancreas—regulates blood sugar by signaling cells to take up glucose and store it as glycogen. In insulin-resistant horses, reduced sensitivity to insulin limits glucose uptake, prompting the pancreas to produce more insulin.

The researchers found that reducing dopamine levels in the horses led to increased postprandial insulin responses. “By temporarily reducing dopamine levels in the brain as well as in the rest of the body, we found that dopamine is not linked to the sensitivity to insulin (in horses, unlike in some other species), but depleting dopamine increases the insulin response to a high-glucose meal,” said Bailey. “Therefore, normal dopamine levels must be helping to keep insulin in check.”

Implications for Treating PPID in Horses

Bailey and his team used the study findings to explore the effects of pergolide—a drug commonly used to treat PPID in horses—on dopamine in horses and ponies with and without PPID. “This drug stimulates the receptors for dopamine, telling the pituitary gland to reduce hormone production, but now we find that it may also affect the pancreas, reducing insulin production,” said Bailey.

However, Bailey added that the drug only partially reduced postprandial insulin response to a high-starch meal, and horses without PPID did not benefit from treatment. “Therefore, in PPID animals or those with equine metabolic syndrome, who are at risk of laminitis due to high insulin levels, they still need to be fed diets low in starch and sugars to avoid excessive insulin levels. Pergolide will not protect them from the effects of high-carbohydrate diets (including lush grass).”

Take-Home Message

Dopamine influences insulin secretion in other species, but its role in equine metabolism has been unclear. Many horses with PPID also experience ID, marked by heightened insulin responses and an increased risk of laminitis. Researchers are still exploring the link between dopamine and insulin production and how this information can be used to more effectively treat horses with metabolic problems. Pergolide had no effect on tissue insulin sensitivity; however, the study results suggest that postprandial hyperinsulinaemia might be limited by this dopamine receptor agonist in animals with PPID and ID. If your horse has metabolic issues, work with your veterinarian to develop an appropriate management and treatment plan.

“We are certainly doing more research in this area to try to better understand these conditions (PPID, EMS, and laminitis) and how they fit together,” said Bailey. “These are such common conditions with huge effects on the well-being of our horses and ponies, so we need to do everything we can in the effort to find new treatments and countermeasures.”

The first study, “Effect of short-term dopamine reduction on insulin sensitivity and post-prandial insulin and glucose responses in Standardbred horses,” was published in Domestic Animal Endocrinology in January 2025. The second study, “Effect of pergolide treatment on insulin dysregulation in horses and ponies with pituitary pars intermedia dysfunction,” was published in Equine Veterinary Journal in February 2025.

Feeding senior horses (typically considered over the age of 15) doesn’t have to be complicated. Some need adjustments to their nutrition as they continue to age based on their health status and body condition. Read on to better understand older horses’ nutrition so they remain happy and healthy into their golden years. Sponsored by Sentinel.

Unveiling what EMS and ID really look like

Equine metabolic syndrome (EMS) is not a single disease, say members of the Equine Endocrinology Group in their most up-to-date guidelines¹ and authors of the ECEIM consensus statement.² Rather, EMS is a collection of risk factors for endocrinopathic laminitis—the leading cause of laminitis in horses caused by hyperinsulinemia (elevated circulating insulin levels). The most consistent feature of EMS is insulin dysregulation (ID), which veterinarians can measure relatively easily in horses. Another feature they commonly see in EMS cases is increased generalized or regional adiposity—fat deposits all over the horse or in certain spots.

“EMS results from an interaction between genetic and environmental factors, and the risk of laminitis in the individual animal therefore depends on the cumulative effects of these influences,” states the Equine Endocrinology Group in the guidelines.

This means genetically high-risk horses can develop EMS with only minimal environmental (e.g., dietary) influences, whereas other horses that have a lower genetic risk might develop EMS with improper environments, such as diets high in nonstructural carbohydrates (NSCs).

In this article we’ll describe horses and ponies with a higher genetic risk for EMS followed by some examples of other animals with lower genetic risk for EMS that might still benefit from EMS (ID) testing.

“Recognizing EMS in horses other than the ones we expect, the overconditioned equine population, is important because even nonobese and athletic horses are at risk of career- and life-threatening endocrinopathic laminitis if not recognized and treated,” says Teresa Burns, DVM, PhD, Dipl. ACVIM, an associate professor of equine internal medicine at The Ohio State University, in Columbus.

The True Face of EMS: Obese Ponies

The overconditioned population with regional adiposity at the tail head as well as a “cresty” neck is truly the face of EMS, especially ponies. Current estimates suggest 22-27% of ponies are hyperinsulinemic (Durham et al., 2019).¹

“If there ever were a poster child for anything, overconditioned ponies are it for EMS,” says Burns.

“Ponies come by their EMS risk honestly, it seems,” she adds. “But as we are all increasingly aware, there are many other breeds at elevated risk, including—but definitely not limited to—American Saddlebreds, Morgans, Tennessee Walking Horses, Paso Finos, and Arabians.”

We need to look for not only generalized obesity but also regional adiposity.

“Recent work in certain smaller populations failed to identify body condition score more generally as a risk factor for certain components of EMS (like hyperinsulinemia),” Burns explains. “Instead, regional adiposity of the nuchal ligament (in the neck) and tailhead remains predictive.”

For more specific information Burns recommends referring to studies by Fitzgerald et al., 2019³; Barnabé et al., 2023⁴; and Lykkjen et al., 2023.⁵

“It’s also probably not an accident that when EMS-affected animals lose weight, some of the very last adipose tissue to be mobilized is in those high-risk depots,” she adds. “Lean animals often retain these fat depots, especially members of those high-risk breeds. The biological behavior of this fat appears different (more inflammatory, more insulin-resistant) and, in that respect, yes, it may be more important in the setting of monitoring and managing EMS.”

In a recent study a Nigerian research group (Akinniyi et al., 2023) examined the occurrence of EMS in two separate populations of horses: one group of polo ponies residing in Igabi (60 horses) and a second group of companion horses owned by emirates in Zaria (56 horses). In total, 67.8% of the companion horses were diagnosed with EMS, and the prevalence of EMS in obese horses was 92.86%. Obese horses were more than 10 times more likely to have EMS than underconditioned (a body condition score of less than 4.5 on the Henneke 9-point scale) horses, and horses with a cresty neck were nine times more likely have EMS than horses with normal neck crests.⁶

Breeds ‘Resistant’ to Insulin Dysregulation

“Any horse that is overconditioned to the point of obesity can develop EMS, so no breed is completely immune,” says Burns.

Amanda Adams, PhD, an assistant professor at the University of Kentucky Gluck Equine Research Center agrees, adding, “But even a ‘resistant’ breed, if they are pushed with diet/management in the wrong direction, can become EMS/ID.”

Breeds that seem more “resistant” to ID include Thoroughbreds, Standardbreds, and Quarter Horses, Burns says.

“But we have seen members of virtually all breeds within our hospital population affected, including those listed above as well as draft horses,” she adds. “That said, it’s pretty uncommon to see members of those breeds affected if they aren’t first very overweight. They don’t seem to have the same degree of underlying genetic predisposition as do some of the high-risk breeds.”

So, why are certain breeds more resistant, yet not immune to ID and EMS?

“These more resistant breeds more than likely have a genetic factor that is protective, and we have yet to identify the genes responsible for this protective factor,” says Adams.

“Research is ongoing in this area to unravel these questions, but this is not straightforward,” she adds. “And as we know, even if you identify the ‘protective’ or ‘susceptible’ genes of being ID, there is epigenetics in which diet/environment can turn these genes off/on to be over-/underexpressed, which can then influence phenotype (the observable characteristics) of the animal. This is why diet and management are critical regardless of genetic makeup in how we manage our horses to prevent them from becoming ID/EMS.”

Akinniyi et al. also reported that even nonobese horses have ID/EMS. Specifically, nine of the 16 horses (56%) that were underconditioned and 18 out of 61 (29%) horses with a moderate body condition were diagnosed with EMS. The researchers suggested EMS could be related to internal fat or a genetic predisposition. Or, obesity might not be the primary cause and other as-yet-unidentified underlying causes of EMS could exist.

“It’s not a one-size-fits-all category,” says Adams. “There are multiple phenotypes of EMS, including the lean-type EMS horses, which is why diagnostic testing for ID is so important.”

Equine Athletes Can Be Affected by ID/EMS, Too

Even athletic horses can have ID and should not be ignored simply because they compete and are presumptively extremely healthy. Part of this is because many equine athletes are, in fact, overweight. 

As Burns points out, this is particularly true in certain disciplines.

In a study published in a 2023 edition of the Journal of Equine Veterinary Science, Shannon Pratt-Phillips, MSc, PhD, and her group at North Carolina State University, in Raleigh, highlighted the fact that in elite hunter competition, ponies are often overweight or obese by conventional metrics.⁷

“Judges of conformation and appearance appear to reward this,” notices Burns. “Conformation and hunter disciplines seem to favor individuals with higher body condition scores.”

“These findings show that elite competition ponies are dangerously overweight and that adiposity may influence performance in a judged event,” state Pratt-Phillips et al. in the study. “This is of grave concern to the horse industry and needs to be addressed.”

Horses involved in athletic competition, however, do have one advantage over their sedentary counterparts: Exercise has a beneficial effect on insulin regulation. Because certain ponies, such as Shetlands, aren’t exercised as frequently as equids of other breeds, this could play a role in why ponies are at a higher risk of developing EMS/ID.¹

In the Nigerian study Akinniyi reported that 67% of the leisure horses rarely exercised had EMS. However, 20% of the polo ponies that were exercised were still diagnosed with EMS.

Eyeing ‘Healthy’ Horses for Early EMS Signs

While obesity, regional adiposity, and cresty necks certainly tip our radar in the direction of EMS, prompting diagnostics, the at-risk breeds can be affected even while lean and young, says Burns.

Adams notes that “early” signs of EMS/ID are not always easy for people to see, leading owners to believe their horses are healthy.

“Early signs of EMS, such as cresty neck and regional adiposity, including fatty accumulation over the shoulders, ribs, above the eyes, and the rump, can be easily missed by owners if they see the horse daily,” she says. “This is why it’s important to consider ID testing as part of a yearly veterinary examination as a preventative measure.”

This will allow veterinarians to give unbiased evaluation of the animal.

“It’s always better to do the testing rather than guessing,” Adams says.

Horses With Concurrent PPID

If a horse has pituitary pars intermedia dysfunction (PPID, aka equine Cushing’s disease), it’s always a good idea to also test for ID in horses showing clinical signs, says Adams.

Burns adds, “About 30-40% of horses with PPID also have ID.”

But PPID doesn’t necessarily need to be considered in all horses with ID.

“Testing for ID may happen when an animal is on the younger spectrum of age scale, and we know that PPID is more prevalent in older horses,” Adams notes. “I also think testing for both conditions when the horse starts to reach about 15 years of age is a good idea.”

Burns agrees, adding, “As testing strategies for both conditions are refined over time, the prospect of screening populations at risk before any clinical signs of disease are present (and intervening appropriately) is becoming more feasible.”

While researchers are still developing concrete recommendations, Burns says many equine veterinary practices are already adding screening tests to their wellness plans for certain demographics, such as annual measurement of endogenous adrenocorticotropic hormone (ACTH, a hormone that’s elevated in horses with PPID, measured at rest) concentration in the fall for individuals over 15 years of age and annual oral sugar testing in the spring for individuals of breeds predisposed to EMS over 4 or 5 years old.

“Again, such screening protocols for either condition in asymptomatic patients haven’t been validated or formally endorsed, but that capability is a shared goal of several research groups that are active in the field currently,” she adds.

After the Unveiling: Control Hyperinsulinemia

After veterinarians diagnose EMS/ID (see TheHorse.com/1116972), their main treatment goal is to rapidly decrease circulating insulin levels to prevent/quickly resolve laminitis. The Equine Endocrinology Group’s first line of attack on EMS is diet. If you own an animal with EMS, restrict his grazing to little or no grass and stop providing treats and grain (concentrate feed). Here are some other recommendations: Feed to achieve or maintain a body condition score of 5, offering only grass hay low in NSC. (Have the hay tested for NSC content and/or soak the hay to reduce NSCs.) Be certain to offer a low-intake ration balancer with a low sugar content (soaking can leach nutrients from the hay). If laminitis does not preclude exercise, incorporate an exercise program into the horse’s routine. Researchers say even low-intensity exercise involving 30 minutes of unridden fast trot or canter to achieve heart rates of 130-150 beats per minute three times weekly is likely beneficial for these horses.

“It’s important to feed less than 12% NSC hay,” adds Adams. “This is the current guideline; however, my research group is working very hard to put science behind this recommendation. This will better help determine what the ‘safest’ percent NSC in hay is to reduce insulin responses postprandially (after a meal).”

For more information refer to Macon et al., 2022 and 2023.^8-10

Adams also points out that owners not only need to feed low-NSC hay but also restrict the amount of hay they offer to 1.5% of the horse’s body weight per day.

For animals not responding to diet and exercise or in cases of severe laminitis, practitioners might need to rapidly correct ID using medications such as metformin, levothyroxine, and the sodium-glucose cotransporter 2 (SGLT2) inhibitors. These medications are not labeled for horses and must be used under the direct supervision of a veterinarian.

Take-Home Message

Adiposity is a key clinical feature of EMS. Given a preponderance of ponies and horses are overweight, veterinarians and horse owners should consider EMS in many of those animals, particularly if they are at-risk breeds. Still, do not discount EMS in breeds at lower risk, athletic horses, and even other apparently healthy horses. “We should now be actively looking outside of the ‘fluffy’ pony paradigm for equids at risk for EMS,” says Burns. “It can truly affect any of them.”

References:

1. Frank N, Bailey S, Bertin F-R, et al. Recommendations for the diagnosis and management of equine metabolic syndrome. 2022. tinyurl.com/cz2wy8kt

2. Durham AE, Frank N, McGowan CM. ECEIM consensus statement on equine metabolic syndrome. J Vet Intern Med 2019;33(2):335–349.

3. Fitzgerald DM, Anderson ST, Sillence MN, de Laat MA. The cresty neck score is an independent predictor of insulin dysregulation in ponies. PLoS ONE 2019;14(7):e0220203.

4. Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ. Relationships between total adiponectin concentrations and obesity in native-breed ponies in England. Equine Vet J. 2023. In Press.

5. Lykkjen S, Stenbakk LK, Holmøy IH. Prevalence and risk factors for laminitis within the Norwegian pony breed Nordlandshest/Lyngshest. Acta Vet Scand. 2023;65:22.

6. Akinniyi OO, Sackey AKB, Ochube GE, et al. Occurrence of equine metabolic syndrome, clinical manifestations, and associated risk factors in Nigeria. J Equine Sci 2023;34(2):29–35.

7. Pratt-Phillips S, Munjizun A, Janicki K. Visual assessment of adiposity in elite hunter ponies. J Equine Vet Sci. 2023;121:104199.

8. Macon EL, Harris P, McClendon M, Perron B, Adams A. Insulin dysregulated horses metabolic responses to forage pellets. J Equine Vet Sci. 2023;133:104991.

9. Macon EL, Harris P, Bailey S, Caldwell Barker A, Adams A. Identifying possible thresholds for nonstructural carbohydrates in the insulin dysregulated horse. Equine Vet J. 2023;55(6):1069–1077.

10. Macon EL, Harris P, Bailey S, Barker VD, Adams A. Postprandial insulin responses to various feedstuffs differ in insulin dysregulated horses compared with non-insulin dysregulated controls. Equine Vet J. 2022;54: 574–583.

Metabolic disorders are becoming more common in horses and, without proper care, can lead to endocrinopathic laminitis. Managing these conditions effectively can be challenging. For horse owners, understanding insulin dysregulation (ID) and implementing effective prevention and management strategies is critical for the long-term health of horses with ID.

What is Insulin Dysregulation in Horses?

Insulin dysregulation compromises the horse’s ability to metabolize soluble carbohydrates. The broad term that encompasses both tissue insulin resistance and elevated blood insulin (hyperinsulinemia). “Not all horses exhibit both conditions, though; some only have insulin resistance, while others may have elevated insulin levels after eating,” says Erica Macon, MS, PAS, PhD, an assistant professor at Texas A&M University, in College Station. “Either condition is a cause for concern in the development of endocrinopathic laminitis.”

When a healthy horse eats nonstructural carbohydrates (NSC, starch and sugar) the digestive enzymes in the gastrointestinal tract break them down into glucose. When blood glucose levels rise, the pancreas releases insulin, which helps the glucose move from the blood into tissues. This then reduces blood glucose levels, and the pancreas reduces insulin secretion in response.

“These horses tend to have some degree of insulin resistance, where insulin fails to do its normal job after a meal rich in NSCs of helping the absorbed glucose to get from the blood and into tissues like the muscle, to reduce blood glucose concentrations back to normal,” says Shannon Pratt-Phillips, MS, PhD, PAS, a professor in the Department of Animal Science at North Carolina State University, in Raleigh. “In these horses the pancreas releases very high amounts of insulin to try to deal with the glucose load and its (insulin’s) reduced effectiveness, but glucose concentrations fail to come back to normal as quickly as healthy horses. Horses with ID tend to also have elevated insulin concentrations even without a previous meal.”

Hyperinsulinemia has been shown to cause laminitis, a painful condition characterized by inflammation of the laminae (the tissue that connects the hoof wall to the underlying coffin bone) that potentially leads to separation and rotation of the coffin bone. In these cases it’s referred to as endocrinopathic laminitis.

Which Horses Are at Risk for ID?

Multiple risk factors can contribute to an equid developing ID. “There is both a genetic and environmental component,” says Macon. “Have you ever been asked during a doctor’s appointment if diabetes runs in your family? Equids experience a similar genetic predisposition to ID and obesity. For some equids their genetics simply aren’t in their favor. For example, Spanish breeds and most pony breeds are more prone to being overweight and developing ID.”

Horses with pituitary pars intermedia dysfunction (PPID, formerly equine Cushing’s disease) are more likely to develop ID. Researchers are still working to fully understand this connection, says Macon.

Although obesity and disorders such as PPID are primary risk factors, horses that do not match that description can also have metabolic problems. “It is possible for a horse to be ID and be lean, or an obese horse to have normal glucose and insulin responses to a simple carbohydrate meal,” says Pratt-Phillips. “Horses that are fed high amounts of NSCs on a regular basis may also have lower insulin sensitivity.”

Even if your horse does not match the usual “at-risk” description, it is important for him to maintain a healthy body condition to reduce his risk of developing metabolic problems. Your horse should not exceed a body condition of 6 on the Henneke nine-point system. “You should always be able to feel a horse’s ribs,” says Pratt-Phillips.

Feeding Horses With ID

If your veterinarian diagnoses your horse with ID, consider a few key aspects of his management. If the animal is obese, work with an equine nutritionist to adjust his diet for weight loss. However, if he has been diagnosed with PPID, work closely with your veterinarian to medically manage him as well.

Regardless of the underlying cause, horses with ID should eat a diet low in NSCs, which you can calculate based on the feed label. “I use NSC (water-soluble carbohydrates plus starch) because it includes fructans,” says Macon. “Now, not every horse responds to fructans, but some horses do, so I like to err on the side of caution.”

The percentage of NSCs in the diet is often a driving factor for horse owners in determining if a forage or concentrate is going to be safe for their ID horse, but the industry is moving away from relying on a percentage.

“When we think about a percentage, we don’t take into consideration where that starch is coming from or how bioavailable it is, so breaking down the actual load on a grams per kilogram body weight (BW) seems to be the better option,” says Macon. “Up until my work, there wasn’t any NSC threshold studies done in metabolic horses.” Researchers have now found 0.1 grams of NSC per kilogram of body weight per meal to be the safe threshold for metabolic horses.

Therefore, when designing your horse’s feeding plan, find the percentage of NSC in the feed, the amount of that feed your horse receives at each meal, and your horse’s body weight. Use the below calculation to ensure you do not exceed 0.1 g NSC per kg BW per meal.

Calculating NSCs in Your Horse’s Meal

Information Needed

1. Horse’s ideal BW
2. NSC % of commercial grain
3. Feeding rate for horse’s ideal BW based on manufacturer’s instructions

Calculation

1. Convert horse’s weight to kilograms.
2. Convert total feeding rate to grams.
3. Ensure NSC % is on a dry matter basis. Pelleted concentrates are 95% dry matter. Textured concentrates are 90% dry matter.
4. Multiply the NSC on a dry matter basis and the feeding rate in kilograms.
5. Divide the grams of NSC in the concentrate by the animal’s BW in kilograms.

Example Calculation

Horse’s body weight = 500 kg

Feeding rate of concentrate = 1,800 g

NSC % = 12% on a dry matter basis

(0.12 NSC dry matter basis) x (1,800 g) = 216 g NSC in the concentrate fed daily

216 g NSC / 500 kg = 0.43 g NSC provided in the concentrate daily

“If your horse’s meal is too high in NSCs, you can split the feeding into more meals per day so that each one is smaller and will have less glucose,” says Pratt-Phillips.

When choosing your horse’s forage, consider both the NSC content of the hay and the time the horse takes to consume it after each feeding. While less research exists in this area, the current recommendation involves providing low-NSC hay (below 10% on a dry matter basis) and encourages prolonged feeding time. “Implementing slow-feeding strategies to make sure that the horse is having a smaller quantity over a longer period of time I think is the safest bet that we can go with right now versus throwing two flakes on the ground and letting them consume it rapidly,” says Macon.

Take-Home Message

Our scientific understanding of equine metabolic problems constantly expands. Understanding ID and which horses are at risk will help you recognize issues with your horse’s metabolic health and seek veterinary intervention. Prevention is also important, keeping horses lean and avoiding obesity to reduce their risk of developing ID. New calculations for determining the NSC content of your horse’s meals can help you accurately determine if his diet is safe for his metabolic health.

Q. I have an upper-level dressage horse that is in a rigorous training program six days a week. He is currently in good condition with a body condition score (BCS) of 5. Because he is working hard, I’m concerned about his protein intake. What are the best sources of high-quality protein for me to look for or add to his feed?

A. Protein is an important part of your horse’s diet and is one of the six required nutrient classes for horses. Taking a keen interest in your horse’s protein intake is important because when a horse’s workload increases, his or her protein requirement increases as well.

Proteins are a major component of body tissues and play key roles in enzymes, hormones, and antibodies, so consuming a quality protein source is imperative to working horses’ health. Protein is also necessary for muscle development and repair, which is necessary for horses in work.

Amino Acids in Equine Diets

Protein molecules are composed of amino acids. There are 21 main amino acids, 10 of which are essential, meaning the horse cannot synthesize them and we must provide them in the diet. The National Research Council’s (NRC) Nutrient Requirements of Horses, published in 2007, provides a recommendation for horses’ crude protein intake as well as lysine intake. Lysine is the first-limiting amino acid for horses, meaning it is the first essential amino acid in which they become deficient. Although equine researchers do not yet know how much of each essential amino acid horses need, we know that lysine, threonine, and methionine are the first three limiting.

High-quality protein is readily digestible for the horse in the small intestine if the protein source is providing the essential amino acids in correct amounts. A lower-quality protein source might not provide the key amino acids or be as digestible.

Evaluating Protein Content in Your Horse’s Diet

Before you focus on the protein in your supplemental products, you should first look at the hay, which almost always makes up most of the horse’s diet. If you are concerned about your horse’s protein intake, first order a hay analysis. Simply adding more protein to your horse’s diet without analyzing your hay first can eventually have negative effects on your horse’s health.

Excess and Deficiency in Equine Diets

In equine diets too much or too little protein can cause health issues. Performance horses maintained on high-quality hay with supplemental feeds are unlikely to have protein deficiencies.

Excess dietary protein is not typically an issue for healthy horses because they can break it down and excrete the excess, but it can put unnecessary strain on the kidneys and liver. Horses do not store protein for later use the way they do carbohydrates and fats.

When horses consume excess protein for a prolonged period, it can increase the horse’s heat production and urine output and create a significant ammonia smell in the stall that negatively affects the respiratory tract. Additionally, protein is a costly feed ingredient so providing it in excess makes the ration unnecessarily expensive.

Choosing A Quality Protein Source for Your Horse

When evaluating protein in the diet, look at the crude protein your hay and feed supply and evaluate the quality of the protein source. Hay provides protein to the horse, and legumes such as alfalfa serve as high-quality protein sources. Other high-quality protein sources include soybean meal, canola meal, flax, whey, sunflower meal, and a variety of legumes. Equine nutritionists typically regard cereal grains (i.e. oats or corn) as lower-quality protein sources.

When reading the label of the feed you have chosen for your horse, instead of just looking at the crude protein percentage, you should also take a close look at the ingredient list. Take note of the protein sources and be conscious of where they lie on the list. Ideally, the higher-quality sources should be at the top of the ingredient list, meaning they make up most of the product’s protein content. If the higher-quality sources are toward the end of the ingredient list, it indicates they make up a smaller portion of the feed’s protein.

Take-Home Message

The crucial first step in planning an optimal diet for your horse is to pursue a hay analysis, which will help you understand how much protein your forage is providing. This information will help you be confident you are meeting your horse’s crude protein requirement. From there, you can critically evaluate your horse’s feed to ensure there are high-quality protein sources in the ingredient list such as alfalfa, soy, canola, whey, legumes, or even sunflower meal. Choosing a commercial feed that mainly includes high-quality protein sources is a good way to ensure the product is supplying highly-digestible protein to your horse.

Q: My easy-keeper horse had laminitis a few years ago, and ever since then I have controlled his hay intake to ensure he maintains an adequate body condition score. My concern is his hay ration does not last him 24 hours, even with a hay net. I have heard that horses should not go without hay, therefore I am wondering what management tactics could help his hay last longer? And should I be concerned when his hay runs out?

A: It is great to hear your horse has maintained a healthy body condition (which should be 4-5 on the Henneke scale) after recovering from laminitis. As you know, it can be very challenging to manage these easy keepers.

You are correct in that it is important to ensure that horses do not have extended periods of time without access to hay. However, for horses that tend to be overweight, they are typically unable to have free-choice hay because this can result in obesity, which is a serious health concern. 

The Importance of ‘Trickle Feeding’ for Horses

The reason horses need access to hay or roughage for most of their time stems from how they have adapted to eat. Horses are trickle feeders and graze for upward of 18 hours per day. Therefore, their anatomy is designed to support trickle-feeding behavior. For example, unlike in humans, when horses chew, it stimulates salivation. Saliva is important for both moistening feed and as a gastric buffer, so it’s crucial to consider chew time when determining how to feed your horse his hay rations.

Additionally, the stomach continually produces gastric acid—even when the horse is not eating. Lack of forage in the horse’s stomach creates a much more acidic environment and can increase the risk of gastric ulcers developing.

There are many anatomical reasons to support trickle feeding, but it is important to keep in mind that obesity is also a serious health issue in horses. It is not always as simple as hanging a hay net and hoping our easy keepers can pace themselves.

How Much Hay to Feed an Easy Keeper

When restricting forage, you must still meet the minimum hay intake of 1.5% of the horse’s body weight daily. For example, a 1,100-lb horse needs to consume a minimum of 16.5 lbs of hay daily. Be sure you are implementing slow-feeding methods, such as hay nets, and offering multiple feedings so the horse is never without hay for longer than four hours.

If you have an easy keeper and he runs out of hay an hour or two before his next feeding, it is not a cause for concern if he seems content otherwise. However, if he is having any prolonged periods (three to four-plus hours) without hay then you might need to consider management changes such as feeding him more often. Additionally, if the horse is displaying unwanted behaviors—for example, wood chewing—during the hour or two he is out of hay, this is a sign that you might need to adjust your feeding schedule. In situations when labor is not easily available, there are a few different automatic feeders on the market that could be used as well.

Hay Quality for Horses With Metabolic Issues

A commonly overlooked aspect of feeding easy keepers is evaluating the energy content of the hay—that is, the calories it offers. If your easy keeper is running out of hay too quickly, testing it to evaluate the energy content should be the first step. Easy keepers should eat Grade 3 or 4 “utility hay” based on the American Forage and Grassland Council grade scale. This is hay that is lower in digestible energy, with acid detergent fiber (ADF) content of 41-45% and neutral detergent fiber (NDF) content of 54-65% on a dry-matter basis.

When we match the quality of the hay to our horse’s needs, it can make the management much easier. For example, with your easy keeper, if you source lower-energy hay, it might mean he can consume more without gaining excess weight, so his daily hay ration could last longer.

Straw as an Additive for Easy Keepers

Another management tactic for these horses is to incorporate some straw into their ration. Straw is the byproduct of cereal crops (what is left over after the grain is harvested). Horse owners can use it for easy keepers because it is low in nutritional value and, therefore, low in energy. Please note that due to straw’s low nutritional value, you should not offer it as the primary forage for a horse, but it can make up to 25% of their forage.

As with any diet change, introduce straw over a minimum of seven days so that the horse can gradually adjust and to reduce the risk of gastrointestinal upset. Another key consideration you should make for any horse, but especially those consuming larger amounts of indigestible fiber, is water intake. Be sure your horse is receiving adequate salt and has free-choice access to a fresh and clean water source.

The goal of either sourcing lower-energy hay or incorporating some straw into the ration is to increase the amount of roughage the horse can consume, which helps prevent any fasting periods and increases chew time without significantly increasing digestible energy intake. Test both your hay and straw prior to feeding it to your horse to be sure it is safe for them. If you are unsure of the safety of a forage source, consult a qualified equine nutritionist prior to feeding it.

Even with lower-energy forage, and incorporating straw, slow-feeding tactics are often still necessary. If you are using a hay net, and your horse is continuing to eat too quickly, you could reduce the hole size of the net, or even double-net the hay to slow him down.

Slow-Feeding Tactics

Anytime you implement a new slow-feeding tactic, for example, double-netting, observe your horses to ensure they can consume the hay. Occasionally, if it is too difficult for them, they could become frustrated and give up on trying entirely.

Each horse is truly an individual, so you might have to experiment with a few different types of hay nets or slow feeders prior to finding one that works best for your horse. As horses get used to eating from hay nets, they become more skilled with it, and you might be able to gradually work them to nets with smaller holes or double-netting. Slowing down their intake is important, of course, but also consider any ways in which you can increase your easy keeper’s movement. You can use hay balls or play around with the paddock setup. For example, using multiple smaller hay nets so horses must travel between them or even setting up a track system are great options to encourage natural movement.

Take-Home Message

Overall, carefully managing easy-keeping horses and those at risk of obesity is imperative for their health. However, it can be challenging to provide them with adequate roughage while ensuring they do not become overweight. So, if your horse is on a good slow-feeding program and you have tested your hay, rest assured that your horse will be fine if he runs out for an hour here and there. However, if he experiences prolonged fasting periods, investigate the various management tactics you can use to reduce his time spent without forage.

Do you have an equine nutrition question?

Vitamin E is an important nutrient for your horse’s health because it supports muscle health and protects cell membranes. This nutrient is an essential vitamin, meaning your horse cannot synthesize it and it must be provided in the diet, and it is fat-soluble. 

Vitamin E is perhaps best known for its antioxidant properties. When the horse metabolizes oxygen, free radicals are produced, which can overload the body and cause oxidative stress. “For horses, vitamin E is the most popular antioxidant (among horse owners), it will scavenge the free radicals to reduce any cellular damage,” says Carey Williams, MS, PhD, professor of animal sciences at Rutgers University, in New Brunswick, New Jersey. Green pastures are great sources of vitamin E but, when this is not available, how do we ensure the horse is consuming the amount he needs?

How Much Vitamin E is Recommended for Horses? 

The National Research Council’s (NRC) Nutrient Requirements of Horses, published in 2007, provides a recommended vitamin E intake level based on your horse’s body weight and workload to prevent deficiency. “An average size horse that is not in work is going to require about 500 IU (international units) of vitamin E daily; however, I recommend 1,000 IU for the average horse as this level to help to accommodate any deficiencies,” says Williams. Horses in heavy exercise or breeding have increased requirements for vitamin E. 

“There isn’t a true known optimal amount for all horses,” says Rachel Mottet, PhD, an equine nutritionist and the owner of Legacy Equine Nutrition, in Ocala, Florida. “There is an established requirement that is recommended to prevent deficiency, yet ‘optimal,’ especially as it relates to equine athletes, needs more work.” 

Further research is required to fully elucidate the optimal vitamin E dose for equine athletes. When a horse exercises, there is exercise induced oxidative stress. This is due to increased amounts of free radicals. Therefore, feeding these animals more vitamin E is thought to be beneficial due to its antioxidant qualities. However, the ideal supplementation amount to optimally support equine athletes has yet to be determined. 

Horses metabolize vitamin E at different rates, Mottet adds, so research into optimal supplementation levels is challenging. “I periodically see horses getting the recommended amount of vitamin E (yet), based on their serum samples, are still deficient,” she says. “Part of the widespread deficiencies I see may be in part attributed to nonviable forms of vitamin E in different supplements, as the vitamin itself is prone to quick degeneration.”

How to Evaluate Your Horse’s Vitamin E Status

Ensuring your horse’s daily ration is meeting the NRC requirements for vitamin E is a crucial first step in evaluating your horse’s vitamin E status.

Because it is not realistic to measure the vitamin E content in pasture and hay, look at what the horse gets in the rest of his daily ration—ration balancer, concentrate, and any top-dressed supplements—especially if he’s on a primarily hay diet or has period of the year where pastures are scarce. Talk to an equine nutritionist or your veterinarian about what you find.

“If you are concerned about your horse’s vitamin E status have the veterinarian pull blood to evaluate,” says Mottet. “As long as the sample is handled properly and submitted quickly, this is a great (and the most accurate) way to determine if your horse is getting an adequate amount.”

If there is a deficiency detected via blood serum, then your horse likely needs additional vitamin E supplementation. “10,000 IU doses are used short term (to rectify a deficiency) as it can interfere with beta carotene absorption (at sustained levels),” says Williams. “Normally, it is not toxic, but you can get to a point that you interfere with other fat-soluble vitamins.”

Mottet adds that it is unnecessary to supplement your horse’s vitamin E intake if blood serum tests do not detect a deficiency.

Best Sources of Vitamin E for Horses

Again, pasture is the best source of vitamins for horses. Sun-cured hay is inevitably vitamin-deficient. “I personally like to make sure that my ration is providing my horse’s daily vitamin E requirement and whatever I get in pasture or hay is a bonus,” says Mottet.

If it’s clear the horse needs vitamin E supplementation, work with an equine nutritionist to be certain your horse is consuming a high-quality bioavailable vitamin E source.

When evaluating vitamin E in a product, there are two main types—natural and synthetic. The synthetic form of vitamin E is known as dl-alpha-tocopherol, and the natural form is d-alpha-tocopherol. “Both natural and synthetic sources work, however, the natural vitamin E is more bioavailable (usable) to the animal,” says Williams. “About 20 years ago my lab looked at heavily exercising horses and if greater vitamin E supplementation would decrease oxidative stress. It was shown that intensely exercising horses that were not housed on pastures would benefit from 5,000 IU per day for a 1,000-lb horse; the synthetic form was used for this research, therefore, if you were using the natural form, you could likely get by with 2,500 IU instead.” 

The NRC’s recommendation is a helpful starting point, but it is important to remember that more is not always better. “If the horse has adequate serum vitamin E levels, there isn’t strong data that says more is better,” says Mottet. “However, as a potent antioxidant it’s possible that additional vitamin E could provide benefits to equine athletes.” 

More research is needed to confirm the efficacy of this supplementation method, she adds. Additionally, although toxicity risk is low, there is a potential for interference with other fat-soluble vitamins when significantly over-supplied to the horse. 

Take Home Message 

Vitamin E is an important antioxidant for horses. Equine athletes in heavy work, broodmares and breeding stallions, or those without daily pasture might need additional supplementation. Natural and synthetic forms of vitamin E are available and, while both are effective, the natural form (d-alpha-tocopherol) is more bioavailable to the horse. Therefore, if your horse has a deficiency, your veterinarian or an equine nutritionist might recommend supplementing him with a liquid form of natural vitamin E from a reputable company. Before adding a supplement to your horse’s diet, consult your veterinarian for blood serum testing, which can help you obtain accurate information about your horse’s vitamin E status.

Q: I’ve struggled to build my horse’s topline. His loin is under developed despite being in regular dressage training. A friend at the barn suggested that I add whey protein to his diet. I am curious to learn if this is a good idea and why it might help.

A: Having a strong back musculature, or topline, plays an important role in your horse’s ability to carry you as a rider in a way that a) protects his spine and other tissues and b) allows him to successfully fulfill athletic demands.

Horses can struggle with topline development for many reasons and, while nutrition can play a role, it’s important to rule out other potential issues. For example, saddle fit and training methods can impact a horse’s ability to use himself correctly and, thus, develop strong musculature. Similarly, pain associated with joints or conditions such as polysaccharide storage myopathy might also have an impact. For this reason, I strongly recommend your veterinarian assess your horse to rule out any other issues before assuming it’s nutritional.

I also recommend body condition scoring your horse and make sure he’s not lacking in condition overall. If you determine that the horse is generally underweight, you’ll probably need to increase calorie intake, as this is likely contributing to your lack of topline. If however you determine that the horse generally has good fat cover, the ribs are covered, etc., but his topline is still underdeveloped, then this might be associated with insufficient dietary protein.

How much protein does a horse need?

How much protein a horse needs depends on the horse and the physiologic state. I rarely find a crude protein deficiencies in mature horses’ diets; they typically only require about 10 or 11% crude protein in their diets, which most forage sources easily meet. However young, growing horses require 12 to 14%, and this might pose more of a challenge to meet.

Most good grass hays can meet mature horse protein requirements and provide 10% or higher crude protein; alfalfa typically provides 18% or more. Grain hays such as oat hay can fall short, with an average crude protein of closer to 8%.

In reality, though, your horse doesn’t have a crude protein requirement, but rather an amino acid requirement. Amino acids are the building blocks that make up proteins, and there are 21 amino acids of which nine are essential for mammals (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine with others being conditionally essential). An essential nutrient is one that must be provided by the diet because the animal can’t make that nutrient itself. Each protein contains a range of these various amino acids with some providing a greater proportion of essential amino acids than others. The greater the proportion of essential amino acids in a protein the better quality that protein is said to be.

In an ideal world the amino acid composition of the diet you feed would exactly match the amino acid needs for your horse. Unfortunately, we need more research in this area before we are close to this level of accuracy in equine nutrition, although other species such as swine and poultry, have feeds more along these lines. The amino acid provided in the lowest quantity compared to the animal’s need is said to be the limiting amino acid. For equine diets lysine is typically the limiting amino acid followed by methionine which is why you often see them being singled out on feed labels with guaranteed levels.

Diet Design Tips

Grass hay is made up of medium- or low- quality protein and does not provide a great deal of lysine. This is particularly an issue if you limit your horse’s hay intake. Alfalfa, on the other hand, provides more lysine, so its protein is considered to be of better quality. Many performance horse owners I work with believe that they see a benefit in their horse’s topline when they feed some of the forage ration as alfalfa, and this might be part of the reason.

Another complicating factor associated with hay protein is that the more mature a hay is, the more protein is associated with the structural carbohydrate fractions. This is potentially important because protein digestion and amino acid absorption needs to occur in the small intestine. However, structural carbohydrates require microbial fermentation to be broken down to release the protein contained within. Microbial fermentation occurs in the hindgut, which comes after the small intestine. Therefore, any protein and amino acids released at that point have missed the opportunity to be absorbed and instead are converted by the bacteria to ammonia. So, while a hay analysis can suggest a particular forage has adequate amounts of protein it’s possible that not all that protein is actually available for the horse. This is likely a bigger concern for grass and grain hays because alfalfa has so much more protein and tends to have higher digestibility.

For your horse to be able to synthesize the proteins, he needs the amino acids be present in the right ratio. If one of the necessary amino acids is present at inadequate levels, this will negatively impact protein synthesis. When you combine the issue of protein quality, protein availability, and the concept of limiting amino acids and the need to have the right amino acids present in the right amounts for protein synthesis, it starts to become clear that all these factors play a role in your horse’s ability to generate anything made up of protein.

If your horse’s lack of topline development is due to dietary protein the goal is to improve the overall protein quality of the ration so that more of the essential amino acids are provided in a digestible format. Skeletal muscle is made up of a broad range of amino acids with the greatest being lysine at about 79 mg/g of muscle tissue, followed by leucine at 77 mg/g and the other branch chain amino acids isoleucine and valine.

It might be tempting to supplement individual amino acids; however, I caution against this because amino acids need to be present in a balanced manner. By giving just one amino acid you run the risk of upsetting this balance. Rather, it’s preferable to provide a source of better quality protein that will supply a range of amino acids.

This is why soybean meal is a common ingredient in horse feed. Soybean meal is the highest quality plant based protein source commonly available as a feed ingredient. Soybean meal provides just more than 60 mg of lysine per gram of protein, which is significantly more than a mid-maturity grass hay with 35 mg of lysine per gram of protein, and even alfalfa with 51 mg of lysine per gram of protein. Correctly offering your horse a commercial feed will often ensure he receives adequate lysine, along with other essential amino acids.

So, what does all this have to do with whey protein?

Whey protein comes from milk and is left after manufacturer’s separate curds from it during cheese making. Once carefully dried to a powder, a highly concentrated source of protein remains. The protein is also very high-quality with more than 60% of the amino acids being essential amino acids, in particular the branch chain amino acids leucine, isoleucine, and valine. With skeletal muscle being made up of a high concentration of these branch amino acids, adequate branch chain amino acid availability is important for muscle repair after exercise. Supplementing horses with whey protein might help support development of lean muscle mass.

However, research in this area is limited and inconclusive. It’s also important to understand that whey protein comes in several different forms. Most commonly available are whey protein concentrate and whey protein isolate. The concentrate is the whey exactly as it was when the curds were removed meaning that it still contains lactose, fat, and various vitamins and minerals. Protein content can vary widely and care needs to be taken as horses over 3 years old are less able to digest lactose, which can lead to digestive distress. The isolate form is a more consistent product and has had much of the fat and lactose removed. As a result, the product is almost pure whey (90% plus) and is considerably more expensive.

Equine whey protein supplements do exist, and I recommend them over those created for people, because those made for people are often for making protein shakes and contain other ingredients and additives that might not be suitable for your horse.

Take-Home Message

If you’re struggling to develop your horse’s topline and feel that there might be a nutrition issue, evaluate your horse’s diet. Consider the sources of protein in the ration and see whether there are easy affordable steps you can take that will improve the overall protein quality and digestibility of the ration. This ultimately might or might not involve supplementing whey protein.

Q. This year was difficult for harvesting hay, so the only hay I could get for my herd of horses has had preservative sprayed on it to prevent mold growth. Should I be concerned about this? Is it safe for them to consume?

A. Harvesting high-quality hay can be challenging for horse owners. To cut and bale premium hay, it must be cut at the right time, dried quickly, and baled at the correct moisture, then moved out of the elements and into storage. Although this sounds straightforward, it can be challenging because it relies heavily on weather conditions. In seasons that have a lot of precipitation, baling adequately dried hay becomes an issue. However, for horse hay, it is crucial that the bales not contain mold and are adequately dried.

Farmers monitor moisture content of forage throughout the harvesting process—when the hay is too wet mold is a concern and those bales could even become a fire hazard, and if the hay is baled too dry, there is significant nutrient loss due to leaf brittleness. Therefore, a happy medium is key.

Farmers might invest in inoculants or preservative sprays to reduce the likelihood of losing a crop because they allow the farmer to bale a hay at slightly higher moisture levels. For example, if the hay is not quite dry enough, but there is rain approaching in the forecast, the farmer might invest in a preservative spray for that field to ensure it can be baled prior to the rainfall. These products are most commonly used in wet and cool climates.

Manufacturers offer two main types of preservatives: bacterial inoculants and organic acids. Bacterial inoculants are typically characterized by the addition of lactic-acid-forming bacteria such as Lactobacillus, Streptococcus, and Bacillus. These organisms compete with mold-forming organisms in order to maintain forage quality. These products allow farmers to bale the hay at 3 to 5 percent higher moisture.

The other common preservative farmers spray on hay is organic acids (e.g., propionic acid). These products produce an acidic environment that is not supportive of mold growth. Again, this allows the hay to be baled slightly wetter so the grower can reduce the amount of time that it is in the field drying with a risk of it being rained on.

Farmers only use these products when absolutely required because they are an investment; however, without them, more hay would be lost in wet years, which would create shortages and cause hay prices to skyrocket.

Regarding horse health, researchers have shown that horses preferentially eat nontreated hay when given the choice. However, it is safe for them to consume treated hay. In one study looking at feeding hay treated with commercial preservatives to yearlings, scientists found there was no difference in feed consumption or weight gain between the treated and untreated hay groups. When we investigate hay treated with propionic acid, keep in mind that the product is buffered; despite it having a very low pH on its own, it is buffered to be closer to neutral (pH of 7) and will not cause harm to the horse when consumed. Additionally, the horse naturally produces propionic acid in the hindgut when hay is fermented.

Although farmers prefer harvesting conditions that allow for the baling of high-quality horse hay without the use of preservatives such as organic acids and bacterial inoculants, these products are a safe and effective way to reduce the risk of mold development in hay. So, from a nutritional standpoint, hay that has been treated with a preservative such as propionic acid is safe for horses.

Do you have a horse nutrition question?

Your horse’s nutritional requirements depend on his life stage and individual needs

All horses need the same essential nutrients—water for cellular, tissue, and organ function, carbohydrates and fats to fuel body functions, protein to build and repair tissues, and certain vitamins and minerals to promote and maintain normal physiological function. Feeding an appropriate diet, however, is not just a matter of tossing them some hay, grain, and supplements. Creating a diet for your horse involves a targeted plan that allows him to use nutrients more efficiently.

To figure out what your horse needs, realize that horses are grazers designed to eat little and often, says Amy Parker, MS, equine nutritionist and technical services manager at McCauley’s, in Versailles, Kentucky. Their natural diet is mainly grass, which has a high roughage content. So, their diet as domesticated animals should be predominantly fiber-based— whether it’s grass, hay, haylage, a hay replacement, or a combination thereof—to mimic their natural feeding pattern.

Parker says the right diet for your horse must reflect his individual needs, taking into consideration factors such as age, weight, body type and condition, health, level of work, and physiological state (e.g., growing, pregnant, lactating). Time of year and weather conditions are also important to consider when formulating the appropriate diet. For example, if the horse gets most of his nutrition by grazing good-quality pasture, then he needs alternative feed sources (i.e., hay) when grass isn’t available. “All of this information provides the foundation to develop the whole diet—forage and feed components,” says Parker.

The National Research Council’s Nutrient Requirements of Horses is the standard guide for feeding horses. Although this text provides much more information than the average horse owner might need, it also offers basic guidelines for energy, protein, and some macromineral (i.e., calcium, phosphorus) amounts based on mature horse body weight. “Once we have met these needs, then the rest is usually okay,” says Shannon Pratt-Phillips, PhD, professor of equine nutrition and physiology at North Carolina State University, in Raleigh.

From Foal to Juvenile

Horses have different nutritional needs depending on their stage of physical maturity. In general, provided a lactating mare is in good body condition and on a balanced diet, we don’t have to worry about feeding the foal because the mare’s milk includes all the nutrients he needs, says Parker. Rather, we consider and select the proper diet when the foal transitions to a weanling and begins consuming solid feed. Young, growing horses need extra energy, protein, and the correct amount of minerals, such as calcium and phosphorus for proper bone and tissue development.

Digestible energy intake greatly influences a young horse’s growth rate, says Pratt-Phillips. In general, the more energy fed, the faster the growth. She says you can adjust diets to accelerate growth in horses earmarked for sale or competition as well as slow growth rates for horses intended to be marketed at a later stage of maturity.

Horses 4 to 6 months of age are defined as weanlings, whereas those 12 to 18 months of age are considered yearlings. Depending on the average daily weight gain you desire for your growing horse, first choose the appropriate forage type to feed. We know pasture alone typically doesn’t meet a growing horse’s nutrient needs, says Laurie Lawrence, PhD, professor of equine nutrition at the University of Kentucky (UK), in Lexington. Further, season affects a pasture’s nutrient content. For the growing season of most legume/grass pastures, the energy and protein content is highest in spring and fall and lowest during the summer.

Lawrence says choosing a hay to match the horse’s needs is a good way to ensure adequate nutrition from the forage. Hay has the highest nutrient value (composition) when harvested in its immature state of growth. Legume hay (alfalfa or clover) is higher in digestible energy, protein, and calcium than grass hay (e.g., timothy or orchardgrass). So, if you are selecting hay, look for the stage of maturity to be between pre-bloom and mid-bloom (prior to the plant flowering) for legumes and pre-head (prior to the plant producing a seed head) for grasses.

Growing horses’ hay consumption varies depending on the hay quality (related to the hay’s maturity at the time of harvest) but usually ranges from 8 to 15 pounds per day for weanlings and 15 to 25 pounds per day for yearlings.

Because feeding growing horses is a balancing act where you don’t want to provide excess or inadequate dietary energy or protein, Lawrence suggests keeping the diet proportions at 30% forage to 70% concentrate for weanlings and between 55/45 and 50/50 forage to concentrate for yearlings.

Average Adult Horses

Mature idle horses can do well on good-quality all-forage (pasture or hay) diets with vitamin and mineral support in the form of a ration balancer, says Parker.

Base forage selection on the type necessary to meet nutrient requirements. For a mature idle horse, this is typically an early to late-head grass hay.

Senior Considerations

Aged or senior horses (18+ years) have additional dietary considerations. They are less able to process and absorb nutrients from feed and have a less efficient microbial population in the hindgut, says Pratt-Phillips. These horses need high- quality pasture and hay with at least a 60% legume content. Senior horses might also develop metabolic problems (such as pituitary pars intermedia dysfunction) that require a specialized diet low in soluble carbohydrates, including warm-season hays that are naturally low in insoluble sugars, such as teff or some species of Bermudagrass.

Pregnant and Lactating Mares

Broodmares’ digestible energy, protein, and macromineral (primarily calcium and phosphorus) requirements jump during late pregnancy (last trimester) and lactation (foaling to three months). For these horses to maintain a healthy body condition, Parker recommends selecting feed that complements the forage to meet the nutrient requirements. For instance, if you feed your pregnant or lactating mare legume/grass hay, add a concentrate feed with moderate protein (12-14%) that is fortified to meet her vitamin and mineral requirements. If you feed a straight grass hay, you’ll need to provide a higher-protein feed. Lawrence recommends offering early to mid-bloom stage legume hays and pre-head to early-head stage grass hays. In general, pregnant mares in late gestation and early lactation consume 70-80% and 50-60%, respectively, of their diet in forage.

Calculating Correct Amounts

Nutritionists generally base their feed recommendations on amounts per kilogram or pound of mature body weight. So your horse’s weight and body condition are essential pieces of information. A livestock scale will tell you the precise body weight of your horse, allowing you to make better decisions about how much feed to provide. You can also make body weight estimations using a weight tape or the body weight formula:

Body weight (lb) = heart girth (in)2 x body length (in)/330

Parker also recommends using the Henneke body condition scoring system (TheHorse.com/164978) on your horse. This system allows the user to evaluate the amount of fat deposition in various body regions, which can guide how much to feed.

Work increases digestible energy needs. The increase ranges from 25 to 50% above maintenance levels with horses in light to moderate work (working five hours or less per week) to 100% above maintenance in horses in heavy work (e.g., upper-level eventing, racing, endurance). Environmental conditions, such as heat and humidity, also affect horses’ dietary requirements due to replacement losses of minerals in sweat.

Choosing Forage Types

You can add forage besides pasture or baled hay to your horse’s diet. These include hay cubes, pelleted hay, chopped hay, dehydrated hay, and haylage. Each poses advantages and some disadvantages, says Parker, but all must be fed based on the product’s weight.

A variety of forage mixtures are avail-able as hay cubes, which are usually 2-by- 2 inches, and can be fed as a substitute for long-stem hay. Horses that waste a portion of their long-stem hay might benefit from consuming a cubed hay, says Robert Coleman, PhD, associate professor at UK. Cubed hay is cut uniformly, thus eliminating sorting issues. Another benefit of hay cubes is you can weigh and store them easily. Cubes are usually made from forage that was cut at an early stage of maturity, giving them a guaranteed minimum nutrient content, says Coleman.

Hay pellets are typically 3/16 to ¾ inch in diameter. They, too, are easily weighed and stored and can be fed as a 100% alternative to long-stem hay with a guaranteed minimum nutrient content. Because hay made into pellets has been ground to smaller particle sizes than hay intended for cubes, horses might consume them faster.

Whether you choose to feed hay cubes or hay pellets, Coleman recommends soaking them in water to soften them for senior horses as well as reduce possible incidence of choke from eating them in their dried state.

Chopped hay is usually chopped to a length of about 1 inch, and you can purchase it bagged. Because of its shorter stem length, this form of hay is easier to chew and might be a good choice for senior horses with poor detention or in a total mixed ration for horses consuming a complete feed.

Dehydrated hay is a chopped hay product that is dehydrated and compressed into a block. The advantage dehydrated hay offers over regular sun-cured hay is it retains its maximum nutrient value with storage. As with the cubes and pellets, this product comes with a guaranteed minimum nutrient content.

Another excellent forage option for horses is haylage, because it provides a high-quality product that is dust-free. Haylage has a moisture content of 20-30% compared to dry hay’s approximately 14% moisture content. In Europe, feeding haylage is common practice, says Coleman. “It looks like regular long-stem hay and has a sweet smell to it,” he says.

Because of the fermentation process involved in making haylage (which increases the level of soluble carbohydrates), this type of forage might not be appropriate for horses with metabolic issues or prone to laminitis. It’s also at risk of botulism contamination if the packaging is not airtight, so ensure horses eating haylage receive a botulism vaccine.

Concentrate Decisions

The final part of creating a diet for your horse is the concentrate. Concentrate, for all intents and purposes, is the nonforage portion of the ration (grains, protein supplements, oils/fats, molasses). Not all horses need a concentrate in their diets. If the horse is at maintenance, for instance, he likely needs only a vitamin/ mineral supplement (ration balancer), says Parker. A concentrate might be an appropriate addition to the diets of horses that cannot get enough nutritional sup- port to maintain optimum condition from hay alone or cannot consume enough hay to maintain optimum condition (growing horses, mares in late gestation or early lactation, horses in intense work, and aged horses).

Parker stresses that the amount of concentrate you feed should be no more than that necessary to provide the horses’ required energy and other nutrients. If your horse needs a concentrate to stay at a healthy weight and body condition, then each feeding amount should provide no more than 0.5% of his body weight.

Final Thoughts

Creating the right diet for your horse involves considering many factors, including the science behind what we feed and how current research and knowledge can help us tailor the horse’s diet to meet his specific needs. Work with your veterinarian or an equine nutritionist to ensure your horse is getting the right nutrients in the appropriate amounts for his lifestyle.

This common pasture grass is good for grazing but bad for broodmares

If you look out over your pasture and see bunch grass with course-textured, flat, and ribbed-surface leaf blades, you are probably looking at tall fescue. Tall fescue, a productive, well-adapted, and persistent cool-season grass is one of the most abundant and heavily utilized forages in the United States. This grass occupies more than 10% of the U.S. land area—­approximately 37 million acres—with an estimated 700,000 horses grazing or fed tall fescue.

From a historical perspective, says Kyle McLeod, PhD, associate ruminant nutrition professor at the University of Kentucky, in Lexington, tall fescue (Festuca arundinacea Schreb.) was thought to have been introduced into the United States as a contaminant in the meadow fescue seeds imported from England until the late 1880s. It was recognized for its ability to thrive and was cited for its superior growth; tolerance of extreme conditions, disease, and insects; and ability to withstand heavy hoof traffic and grazing. By the 1940s two cultivars were released: Alta and Kentucky-31 (KY-31). Alta was selected for its winter hardiness, persistence, and ability to remain green even during drought conditions. This cultivar was planted throughout the Pacific Northwest and intermountain regions of the western U.S. The Kentucky-31 cultivar was noted for its adaptability to a wide range of soil types and ability to provide grazing throughout much of the year. The southern U.S. experienced a wide planting of KY-31 for forage, soil conservation, and roadside coverage. To date, tall fescue ranges from Florida to Canada.

Because of its nutrient composition and agronomic traits, tall fescue is the forage base of most livestock enterprises, particularly beef cattle. Jim Henning, PhD, former extension forage professor at the University of Kentucky, says well-managed fescue produces a high-quality forage with crude protein (CP) and digestible energy (DE) concentrations from vegetative (the period of growth between germination and flowering) to boot (the reproductive stage when the seedhead is enclosed within the sheath of the flag leaf) to mature stages of growth, ranging from 11% to 16% CP and approximately 60 to 68% DE (mature to vegetative).

Tall Fescue’s Side Effects

Despite all its positive traits, tall fescue is not without shortcomings. By the 1950s, says McLeod, fescue had gained a reputation for causing poor performance in livestock—primarily cattle but also small ruminants and horses—­consuming the grass. Cattle often developed a chronic, unthrifty condition, especially during the summer. Some occasionally developed lameness and lost portions of their feet and tails during fall and winter. Other perceived side effects included failure to shed winter coats, and, thus, heat intolerance, and reduced conception rates. Mares on tall fescue appeared to have higher foal mortality and agalactia (absence of milk production).

Scientists began studying the cause of these signs, says McLeod, and by the mid-1970s USDA researchers discovered an endophytic fungus that infects the fescue plant. “Endo” (within) plus “phyte” (plant) means a plant that lives within another plant. In this case the host is the fescue plant, and the toxic endophyte is a fungus identified as Epichloe coenophialum. Two characteristics of the endophyte have great practical importance. First, the organism does not affect either the growth or the appearance of the grass, and it requires a laboratory analysis to detect its presence. Second, it is transmitted solely by seed. So, the endophyte is beneficial to the plant but toxic to grazing livestock.

Krista Lea, MS, horse pasture evaluation program coordinator in the Department of Plant and Soil Sciences at the University of Kentucky, says the toxic endophyte produces several ergot (fungus) alkaloids (nitrogen-containing metabolites of the plant), including ergovaline, ergotamine, ergocristine, and lysergic acid, with ergovaline being the most prevalent (84-97% of the total ergot alkaloids produced). Although all classes of horses can experience endophyte-related issues, pregnant mares develop the most pronounced problems.

Lea says pregnant mares grazing endophyte-infected fescue might carry their foals several weeks past their due date, resulting in dystocia (difficult birth) because of the increased size of the foal. Thickened and/or retained placentas are common for mares grazing endophyte-­infected fescue. Frequently, the foal arrives normally but is encased in a tough and thickened chorioallantois (membrane surrounding the foal in the placenta), which he cannot break through. Consequently, he might suffocate unless someone cuts open the chorioallantois immediately. Premature placental separations (commonly referred to as red bag deliveries) are also common in mares grazing toxic endophyte-infected fescue.

Further, says Bob Coleman, PhD, PAS, associate equine extension professor at the University of Kentucky, mares grazing endophyte-infected fescue produce reduced amounts of or no milk and colostrum (antibody-rich first milk). Colostrum might contain lower concentrations of the antibody immunoglobulin G (IgG) and, in some cases, IgG absorption is lower in foals born to mares grazing toxic endophyte-infected fescue.

Scientists don’t know the exact mechanisms that cause these reproductive problems in mares; however, they do know the ergot alkaloids are agonistic to ­dopamine (D2) receptors, meaning they cause excess dopamine production. Research conducted in 2000 by now-retired Marc Freeman, PhD, and colleagues in the Department of Biological Sciences at Florida State University, in Tallahassee, revealed a significant reduction in circulating and releasable prolactin (a hormone essential to the final stages of birth) from the anterior pituitary gland and agalactia in mares grazing endophyte-infected fescue. Another contributing factor to prolonged gestation is suppression of the hormone progesterone. Progesterone levels should increase about two weeks before parturition (foaling), but mares consuming endophyte-infected fescue have reduced progesterone levels.

Grazing endophyte-infected tall fescue does not appear to have as much impact on other classes of horses, says Coleman. In one study conducted at Auburn University, researchers looked at the growth and development of yearlings grazing endophyte-infected fescue pasture. In another study a team at the University of Georgia considered the growth and development of yearlings eating endophyte-infected tall fescue hay. Neither research group found significant differences on average daily gains or wither heights of horses consuming fescue compared to controls.

A team from Missouri State University evaluated performance horses fed endophyte-infected fescue seed mixed in their grain ration and found no significant impact of the infected fescue on the parameters measured. Lea says researchers at the University of Kentucky have tested ergot alkaloids’ vasoactivity (ability to cause blood vessels to contract or dilate). While they documented vasoconstriction, with ergovaline being the most vasoactive ergot alkaloid, the horses did not appear to be outwardly affected.

Measuring Endophyte Levels

So, what can breeders do from a management perspective to avoid tall fescue toxicity in broodmares? Lea and Coleman agree that pasture management is the ideal option.

The first step is to know for certain the pasture is infected and at what level. For specific sampling procedures, costs, and shipping requirements, contact your local county Cooperative Extension office. However, here are some general sample collection guidelines:

When to sample. Samples must be collected when the plant has been actively growing for at least a month; this provides the best opportunity to find any endophyte present.

Collection. Gather tiller (stem) samples of the plant that are at least 1/8-inch thick. Cut with a razor or sharp knife at the soil surface, avoiding stems that have seedheads. Take at least 10 to 20 random tillers per five acres to get a representative sample of the pasture.

Storage. Place samples with a cold pack in a sturdy, plastic-lined box to take to a county extension office or overnight express to a testing laboratory. Refrigerate samples to ensure sample quality.

Results. The report you receive will indicate the percentage of submitted tillers that were infected with the endophyte. Some U.S. laboratories also determine ergovaline concentrations.

Lea says ergovaline concentrations vary seasonally and closely follow the tall fescue’s cool-season growth curve, with spikes occurring in spring and fall. However, some farms do not test for ergovaline concentrations. Based on data collected over the past 15 years through the University of Kentucky’s Horse Pasture Evaluation program, Lea’s team has developed a relative (ergovaline was not tested or tested outside of the normal months) risk scale to help breeders manage late-term mares’ grazing. Here is an excerpt from the table:

Because the ergovaline produced by the endophyte is what causes problems in broodmares, knowing how much ergovaline the mare is ingesting will provide you with more detailed information to guide your management practices. Researchers have shown that signs of fescue toxicity appear in pregnant mares consuming fescue testing greater than 300 parts per billion (ppb) of ergovaline. However, most extension publications suggest using 200 ppb as the threshold value. The University of Kentucky team has established risk levels for late-term pregnant mares based on ergovaline concentrations in the total diet (see table below).

Most pastures are not 100% tall fescue, says Lea. Pastures contain other grasses and legumes mares prefer to eat, thus diluting the actual amount of ergovaline in the pasture. You can calculate the amount of ergovaline in the pasture based on the estimated percentage of other grasses or legumes in the field, using this formula:

% tall fescue
_________________
(% tall fescue + % grass A + % grass B) x ergovaline (ppb)
=
ergovaline in available forage

From this calculation you can determine your mare’s risk level for grazing a pasture.

Management Strategies

Remove pregnant mares from any pasture (or hay) containing endophyte-infected tall fescue 60 to 90 days pre-foaling, says Coleman. You might move mares to a drylot area where you can meet their nutrient requirements with hay and concentrate or to a pasture with forage species other than endophyte-infected tall fescue. Agronomists and researchers consider this the most conservative way to avoid toxicity problems.

For mares in the moderate to high-risk category, you can administer domperidone, a drug that stimulates normal prolactin and progesterone production, to avoid agalactia and dystocia. Domperidone should be administered daily for 30 days prior to foaling. Grazing and/or mowing the pasture will keep the fescue plants young and in the vegetative state. Coleman stresses the importance of not overgrazing the pasture, because the endophyte is in the basal part of the plant in addition to the seedheads. Don’t let the horses graze the grass below 3 inches, says Lea.

You can also dilute endophyte-infected tall fescue in a pasture by incorporating other grasses and legumes. Because tall fescue is not the most palatable grass, mares will choose not to eat it if something more desirable is available. With this strategy you will also benefit from improved pasture quality and production.

Although an expensive option, the final management strategy might be to kill infected stands and replant. Lea says there are essentially three types of tall fescue:

1. The toxic endophyte, naturally occurring Kentucky-31. This is a very hardy and persistent grass and is the one causing the toxicity problems—it’s the type you are trying to get rid of in your pastures.
2. Endophyte-free tall fescue (e.g., Teton II, Select, Tower, Bronson). This grass does not contain an endophyte, so it is safe for horses to graze. Its downside is it’s not very hardy and cannot tolerate heavy grazing. If you plant this tall fescue, be ready to reseed repeatedly.
3. Novel endophyte tall fescue (e.g., Jesup MaxQ, Tower Protek, Kora Protek, BarOptima PLUS E34, Estancia ArkShield, Martin 2 Protek, Lacefield MaxQII). The endophyte contained within this plant still provides it with hardiness but does not produce the toxic compounds; therefore, horses can graze this fescue safely. Consult your local herbicide dealer to determine the best option for renovating your pasture.

Take-Home Message

Because tall fescue is a popular and well-established grass across pastures in the U.S., eliminating the risk of toxicosis in broodmares is nearly impossible. The only way to avoid fescue toxicosis is to understand the nature of the plants in your pasture. Know when ergovaline levels will be high, and choose the most beneficial management options to reduce the risk to broodmares