It probably comes as no surprise that a horse taking on the rigors of a 100-mile endurance race or a three-day event might need a different diet from one that ambles the trails around home or carries a child through the occasional weekend show. The question is, just how should the feeding plan differ for these high-performance equine athletes? Read on to find out what the experts say.

Counting Calories

The first concern when analyzing a performance horse’s ration is making sure there are enough calories for basic maintenance needs as well as the added energy requirements of high-level exercise, explains Amy Gill, PhD. An independent nutrition consultant based in Frankfort, Ky., Gill has worked with such equine feed companies as Cargill Animal Nutrition (Nutrena) and Alltech, Inc., as well as individual farms.

For horses, calorie intake is measured in megacalories (Mcals) of digestible energy. Digestible energy (DE) is literally the amount of energy in the diet that is absorbed by the horse, says Joe Pagan, PhD. Pagan is president of Kentucky Equine Research, which was recently named the official nutritionist of the U.S. Equestrian Federation and which has supplied equine feed to the last two Olympics.

“The driving force behind performance is the conversion of chemically bound energy from feed into mechanical energy for muscular movement,” says Pagan. In short, as the level or intensity of performance increases, so does the horse’s energy requirement. (See The National Research Council’s recommendations for daily caloric intake based on performance intensity on page 66