If the performance of gallopers and trotters depends on the genetic potential and the training of the horse, a diet mainly of hay, adapted to the athletic horse allows it to be optimized while respecting the physiology of its digestion and its well-being. A ration based on hay is the essential fuel for the metabolism of the racehorse. Hay should be the basis of his diet, concentrates should only be a supplement. The consumption of fodder is very important, it covers most of its nutritional needs, maintains its intestinal flora, provides digestive comfort. Intake of fiber prevents the risk of developing gastric ulcers. For these athletes who are most of the time in the box outside of training, the hay ration also provides them with entertainment and thus limits behavioral disturbances.