Feeding the Equine Athlete

by Beth Stelzleni of Mars Horsecare US, Inc.

Horses that are in training or showing have vastly different nutritional needs than horses that are inactive. But it’s the level of activity is what determines how to feed our performance horses. The NRC categorizes the different activity levels into four categories: light, moderate, heavy, and very heavy. Horses in light activity are those used for events such as trail and pleasure, where the work is mainly done at the walk level – and generally working 1-3 hours per week. Those in moderate work include school horses in a lesson program and those used for frequent showing — but in disciplines that are less strenuous, and these horses usually work for 3-5 hours per week. When we get into the heavy work category, we start to see horses that work for 4-5 hours per week but undergo strenuous speed or jumping work during their training — polo horses and those in low to medium level event training for example. Horses in very heavy work spend the bulk of their training doing strenuous activities including speed and jumping work and may work anywhere from 6-12 hours per week. These include elite racehorses and elite event horses. The higher the intensity of the work, the greater the energy requirement will be.

Energy is the first nutrient that is required in higher amounts in the working horse, but the source of that energy is just as important as the amount. The first source of energy we see in equine nutrition products is soluble carbohydrates, or sugars and starch — found mainly in grains, like corn, and sweetening agents like molasses. When a horse digests soluble carbohydrates, they are absorbed in the small intestine. The problem with soluble carbohydrates is that when they are digested they cause an increase in blood glucose and insulin that can lead to metabolic disturbances and increase the risk for tying up and ulcers, so it’s critical that we don’t overload the small intestine with them. If this happens, the starch that doesn’t get digested in the small intestine goes to the hindgut where it is fermented, which can cause acidosis, diarrhea, and even laminitis.

If starches and sugars can be dangerous when fed in high amounts, what can we substitute as a safer energy source? And the answer is Fats - and these are actually the preferred energy source of the horse. As we train our horses and they increase in physical fitness, their bodies actually shift naturally from using carbohydrates for energy to using fats. Fats are also more energy-dense, meaning that a small amount of fat can actually hold a much larger amount of energy. Like sugar and starch, fats are absorbed in the small intestine but they do not cause a large metabolic disturbance, so they are safer than sugars and starches. Some sources of fats common in horse diets are vegetable oils (such as corn or soybean oil), flaxseed and rice bran.

Fats also provide some additional benefits to performance horses. They improve the skin and haircoat, which is important in the show ring, for example. Fats can also calm behavior and make a horse more manageable. They reduce the heat load and delay lactate build up, both of which help to delay fatigue so the horse can go for longer periods. And since fats are power packed, we can feed less — and the horse has a lower intake so carries around less gut fill. By lessening the gut fill, we can reduce the amount of weight the horse carries and therefore help him to jump higher or run faster.

In addition to energy, water is a nutrient that is greatly affected as the horse starts to work. Performing horses lose massive amounts of water as they sweat, and this water needs to be replenished to keep the horse healthy. In moderate climates, horses can lose 6-8 L of sweat per hour, and this loss can increase to 15 L per hour in hot and humid climates. One L of sweat weighs about 2 pounds, so in a hot climate a horse can lose up to 30 pounds of bodyweight per hour. This is a huge amount of loss that needs to be replenished.

There is a common myth in the horse industry that says we should not let a hot, tired horse drink because it will make him founder or colic, and we shouldn’t let them drink cold water for the same reason. But actually, withholding water is the worst thing you can do when your horse is hot or tired — your horse has his greatest thirst immediately after exercise. If we withhold water until he isn’t hot anymore, he may not feel thirsty – and he could still be in need of water. Numerous studies have shown that letting a hot horse drink will neither cause colic nor founder. In fact, letting a hot horse drink is the best way to help him cool down. Water that is ice-cold is safe as well and won’t cause any health problems — the only potential problem we could see is that the horse may not drink as much, so he may not get the water amounts that he needs. As a rule of thumb, allow your horse water at all times, whether he is hot or not.

Electrolytes are another class of nutrients that working horses need. They should all have free choice access to a salt block… but performance horses need a little extra in terms of electrolytes – and there are many choices available. The first is top-dressing, or adding an electrolyte powder directly to the grain mix. You can also dissolve electrolytes in water. Some electrolytes are available in paste form, or you can create your own paste by mixing a commercial electrolyte powder with applesauce or plain yogurt.

Along with electrolytes, vitamins play a large role in the health of the performance horse. Fat soluble vitamins include Vitamins A, D, E and K. Vitamin D is made by the skin in response to sunlight, and Vitamins A, E and K come primarily from fresh, green forages. Water soluble vitamins include the B-vitamins, thiamin, riboflavin and Vitamin C. Vitamin C is a nutrient we’re beginning to realize as very important in the performance horse. Vitamin C works closely with Vitamin E as an important antioxidant.

While the performance horse does have increased vitamin requirements, these needs usually increase in proportion to energy. In other words, if we feed our horses better grain and hay, or increase the daily amounts fed in the horse’s diet, generally we are already meeting these vitamin needs. The one exception to this may be Vitamin E, which is critical in protecting the body from oxidative damage. This is increasingly important in the working horse, as the muscle breakdown and rebuilding these horses go through can increase the oxidative products in the body. Vitamin E is found mostly in fresh green grass, so if you have a hard working horse that has little or not access to pasture it may be a good idea to supplement with Vitamin E.

So we’ve talked about other nutrients, but what about protein? Doesn’t a working horse have higher protein needs? Well, yes, but not to the extent most people think. What we actually see now in the performance industry is horses being overfed protein. Excess protein is detrimental as it can stress the liver and increase fatigue and dehydration. And since excess protein cannot be utilized for energy in the body, it is excreted in the horse’s urine as ammonia. Which as we all know, has a very bad smell when it builds up on the stall floor and can cause respiratory problems in horses.

With protein, it’s all about QUALITY, not quantity. Horses need grams of amino acids, not just a percentage of crude protein. Providing a high quality protein source (such as soybean meal) is vital in giving the horse the building blocks he need to build strong muscle and bone. It doesn’t matter how much protein we give them—if this protein is of poor quality and doesn’t have the correct amino acids, the horse can’t use it – and it’s excreted in the urine.

Now — a few general rules of thumb to remember when feeding any horse, but especially the performance horse.

• First - always develop your horse’s diet around his hay – the most important part of the horse’s ration.
• Second, know the exact amounts of starch and sugar in your horse’s grain mix. You have a right to demand to know this information from your feed company.
• And finally, it’s always a good idea to work with a qualified equine nutritionist to plan your horse’s diet. They can recommend the best grain to complement your horse’s hay type and keep your horse healthy and happy.