When considering the “performance” horse, images of racing, polo and grand prix jumping come to mind. However, there are many levels of performance to consider, rather than just the elite athlete. Performance horse feeding goes back to ancient Roman times, because even thousands of years ago people realized horses needed additional energy to “perform” in war. Despite this long history of feeding equine athletes, a dramatic increase in knowledge of nutrition has occurred in the past 20 years. 

David Marlin, PhD, founder of Science Supplements, described those changes at the University of Maryland’s Department of Agriculture and Natural Resources’ 2016 Mid-Atlantic Nutrition Conference, held March 23-24, in Hunt Valley, Maryland.

Have feeding recommendations changed? 

In the last 50-plus years, it’s safe to say that the anatomy and physiology of the horse’s gastrointestinal system hasn’t changed—evolution doesn’t work that fast. What has changed is our knowledge about equine nutrition, along with an increase in the prevalence of nutrition-related problems, such as obesity. Changes in feeding practices have likely altered the microbiome of the equine hindgut, although it is difficult to track these changes precisely.

Despite what’s known, different commercial grain concentrates (in similar categories) in the United Kingdom varied widely in the amounts of digestible energy, protein, Vitamin A, and other nutrients they contained. The formulas between products varied, with some being well-over-nutrient recommendations and others falling below. This is important, said Marlin, because “what we feed horses does have an effect on how they perform.”

For example, starch has gotten a bad reputation lately, he said. But starch isn’t all bad. In fact, low-starch diets have been linked to poor performance in horses who are considered high-level athletes. Studies suggest that horses consuming diets low non-structural carbohydrates have lower muscle glycogen concentrations and do not completely replenish muscle glycogen stores 72 hours after depletion. This affects performance animals that competes on multiple, or successive, days in a week and underscore the necessity of tailoring a horse’s diet to individual needs.

Changes in how the “hard working” horse is fed

Hay and pasture have remained staples in equine diets. Today, horses tend to get less forage and pasture, with more commercial concentrates. Grains, pelleted feed, oils, and supplements have been introduced to the diet, not to mention medications and anthelmintics that can potentially alter the microbial population in the GI tract, Marlin said. It is well known that diet affects the microbiome, and potentially the immune system. Thus, he noted, it’s possible that—based on current feeding practices—we have selected for a different hindgut environment. The implications of these changes have yet to be fully understood.

Take-Home Message

In recent history, athletic demands have increased, feeding has gotten more complex, and forage quality for many horses has improved. Unfortunately, nutritionally related problems are also on the rise.

While these things have gone together, Marlin cautioned, that “we should never confuse association or correlation with cause and effect, but the timing is worth considering.”

Peer-reviewed scientific research, books by experts, and the National Research Council’s consensus publication, Nutrient Requirements of Horses, are good places to start for referencing best feeding practices and educating horse owners. If additional questions arise, it’s advisable to contact an equine nutritionist or veterinarian for help in formulating the ideal diet for your performance horse.

Why do horse owners use feed supplements? Ask 10 different owners, and you’ll probably get 10 different answers. But if you ask David Marlin, PhD, founder of Science Supplements, suggests that typically, he’ll say owners are generally looking to solve a particular problem when they elect to feed a supplement.

Agar et al. (2016, Veterinary Record) have also learned that the majority of riders perceive a difference in their horses after feeding supplements. But, is this a real change or a placebo effect? There is still much to be studied regarding the efficacy of many supplements.

At the University of Maryland’s Department of Agriculture and Natural Resources’ 2016 Mid-Atlantic Nutrition Conference, held March 23-24, in Hunt Valley, Maryland, Marlin described commonly fed supplements and deconstructed the theories behind their use:

• Calcium: Marlin said supplementing calcium for calming effects horses has become a trend in the U.K. and Europe. While many horse owners feel it works, there is no evidence to prove it does, he said. Plasma calcium concentration is strictly regulated by the horse’s body, which he said begs the question: Does supplementing calcium really have a significant impact?
• Cobalt: Cobalt is a trace element that is required in very small doses, but is essential to vitamin B-12 makeup. Marlin said cobalt could potentially contribute to an increase in erythropoietin (which stimulates red blood cell production), possibly resulting in a performance-enhancing effect. Excessive cobalt can also act as a carcinogen and cause cardiovascular problems, reproductive disorders, and blood problems. The use of cobalt in equine sport is under intense scrutiny and supplementation above basic requirements has been banned by many racing jurisdictions.
• Electrolytes: Electrolyte balance is important in the equine athlete. Too many electrolytes in the system can deter a horse from eating it. Additionally, oversupplementation will cause the horse to drink more and the kidneys to work overtime to maintain proper physiologic balance. On the other hand, too few electrolytes can cause poor performance, fluid imbalances, episodes of tying up and/or thumps (synchronous diaphragmatic flutter), and chronic electrolyte depletion. Marlin said undersupplementation and chronic deficiency appears much more common than over-supplementation. He cautioned that many horses do not adequately regulate salt intake from salt blocks/licks. As such, Marlin recommended that equine athletes be offered electrolytes in daily feed based on workload and weather conditions, aiming for a slight excess.
• Turmeric/Curcumin: Turmuric can contain 3-4% curcumin—which is thought to have anti-inflammatory and anti-cancer properties—and its popularity has recently exploded in Europe. Despite a sharp rise in scientific publications about turmeric, few examine efficacy in horses. While both turmeric and curcumin are considered natural herbal supplements, this does not automatically qualify them as safe, Marlin said. Adverse effects have occurred in humans, including contact dermatitis, loose bowels, and decreased appetite.

Take-Home Message

There’s copious information—and misinformation—about supplements circulating on the Internet, and Marlin said the use of social media has led to an explosion of inaccurate and misleading information regarding supplements. Supplements are sometimes legitimately needed and quite appropriate to fill a gap in the diet, while other times they aren’t needed at all. As such, owners should turn to equine nutritionists, Extension specialists, and veterinarians with their questions regarding horses’ diets and potential problems with creating a dietary imbalance.

Amino acids (AA) are the building blocks of all proteins and are essential for a number of physiological functions within the equine body.

Kristine Urschel, PhD, associate professor of animal science at the University of Kentucky, in Lexington, shared the functional importance of AA and protein in exercising horses during the University of Maryland’s Department of Agriculture and Natural Resources’ 2016 Mid-Atlantic Nutrition Conference, held March 23-24, in Hunt Valley, Maryland.

Horses’ bodies are mostly made of muscle, which makes up 40-55% of their body weight. Muscle contains roughly 70% water, 20% protein, and 10% fat, glycogen, vitamins, and minerals. Proteins comprise the bulk of solid skeletal muscle, and therefore are of particular interest in exercise physiology, Urschel explained

Exercise increases muscle protein “turn over,” meaning the body breaks down and re-synthesizes protein—an important cycle for building muscle. “However, the process is not uniform throughout the body,” Urschel said “The effects of exercise on plasma AA concentrations have been well-studied, but the implications are varied.”

Plasma AA concentration is only snapshot of every internal process at any given moment in time, so it’s difficult to determine exactly where a change might have come from, she explained In general, an increase of essential AAs in the plasma could mean increased protein breakdown, and a decrease in essential AAs could indicate that the AA is being broken down for use as energy source.

How Much Protein?

There has been some controversy about dietary protein requirements as exercise demand increases, Urschel said. However, the Nutrition Research Council currently recommends greater protein intakes in exercising horses compared to sedentary horses. In horses, only the requirements for crude protein and the AA lysine are known. Requirements for other AAs, such as methionine and threonine, are often estimated based on what has been measured in skeletal muscle.

In a healthy horse, overfeeding protein simply creates expensive urine, Urschel said, because excess protein is broken down and excreted as urea. This process, however, requires energy and water and might have environmental concerns as the horse’s body produces and eliminates ammonia and nitrogen.. If protein intake is insufficient, clinical signs such as loss of weight and muscle tone and poor hoof growth and hair coat could appear, Urschel said.

Amino Acid Supplements

Several protein and AA supplements on the market are aimed at modifying behavior and building muscle. For example, the AA tryptophan is marketed as a calming supplement. Tryptophan is a precursor to serotonin, a hormone associated with sleepiness. However, the few of studies in horses have found no effects of oral tryptophan supplementation on the onset of fatigue or behavior modification, Urschel said.

Branch chain amino acids (BCAAs) are purported to do the opposite. These BCAAs compete with tryptophan for transport to the brain, therefore delaying fatigue. Data is limited and no real scientific conclusions can be drawn. 

Creatine, a compound made from three AAs, is marketed as an energy supplement. In horses, no improvements were found in performance after creatine supplementation. Creatine is only found in the muscle, Urschel noted, and. since horses did not evolve eating meat/muscle, they probably have no means to absorb it from the digestive tract.

Take-Home Message

Protein and AAs serve many important roles in the body. Muscle protein synthesis can be influenced by many factors, such as diet and exercise. Unfortunately, there is very little scientific data to support supplementation of AAs, but more research is certainly needed to gain a better understanding of requirements and function.

Elite show jumpers are the frequent flyers of the horse world, soaring over massive fences with room to spare, while also collecting air miles while traveling between competitions. Not unlike jet planes that fill up with petrol before every flight, jumpers need the appropriate fuel to make it over the fences cleanly and within the time allowed. But the added stress and logistics of international transit can make getting a consistent diet difficult. So how are these horses getting the nutrients they need to stay successful? One researcher recently sought to find out.

Shannon Pratt-Phillips, MSc, PhD, associate professor of animal science at North Carolina State University, sought to gain nutritional information about show jumpers, so she surveyed owners and managers of these elite athletes in active competition. She presented her survey findings at the University of Maryland’s Dept. of Agriculture and Natural Resources’ 2016 Mid-Atlantic Nutrition Conference, held March 23-24, in Hunt Valley, Maryland.

In response to Pratt-Phillip’s survey, managers reported getting the bulk of their nutrition information from the Internet, magazines, veterinarians, farriers, and feed companies.  Additionally:

• Managers weren’t utilizing independent nutritionists;
• Many horse/rider teams were supported by feed companies and often followed manufacturers’ recommendations; and
• Some managers wanted to know more detailed nutritional information, while others were satisfied with the status quo. 

Top nutrition-related health concerns among the managers surveyed included ulcers and lameness. Interestingly, most managers reported feeding the hay provided by the competition facility, which was often of poor to moderate quality, without mixing in hay that the horse was used to eating. However, horses had access to hay the majority of the time they were stabled.

The survey showed that most, if not all, of the show jumpers received supplements including electrolytes, joint support, probiotics, and others. A majority also received daily GastroGard/UlcerGard (the USDA-approved treatment and preventative doses of omeprazole, respectively, used to manage equine gastric ulcers).

The show jumpers’ dietary intake of calories, crude protein and calcium generally exceeded the minimum recommendations of the National Research Council (2007) for horses weighing 500 to 600 kilograms (roughly 1,100 to 1,300 pounds) in heavy exercise, but the horses did not carry excess body weight, Pratt-Phillips said. Phosphorous intake appeared to be below minimum requirements, she added.

Pratt-Phillips also observed that the show jumpers generally ranged from 3.5 to 6.5 on the 9-point Henneke Body Condition Scale.

As a result of the survey, Pratt-Phillips said new questions associated with feeding elite show jumpers arose, such as:

• What is an ideal body condition for a show jumper?
• Horses often compete several days in a week. Is skeletal muscle glycogen repletion an issue?
• Does the diet provide enough energy to support the horse’s workload?
• How does international travel affect a horse’s dietary needs?

Take-Home Message

Keeping hay supplies consistent is still a major challenge when it comes to international travel, Pratt-Phillips said, and she encouraged owners and managers to insist on high-quality hay and forage options at competition venues.  

Owners and managers should also focus on feeding a consistent supply of good quality hay, she said, or even hay cubes if it hay bale transport isn’t practical. Concentrates should be fed at least five hours prior to competition, while hay can be fed two to six hours ahead of exercise.

Most importantly, she added, working with a nutritionist to develop a feeding plan and learning about best feeding practices will help ensure diets meet elite athlete’s nutritional requirements.