Many horse owners have selected for genetically fast growers in recent years because of premiums paid for these animals in yearling sales, and the need for horse use at early ages in many competitive events. It has been suggested that with this type of selection has come increased incidence of skeletal leg disorders. Nutritional studies have indicated that both level of intake and ration composition play important roles in altering rate and composition of gain, although nutrition cannot overcome an animal's poor genetics or a poorly designed exercise program. The generally-accepted recommendation is to maintain young horses in a moderate body condition to promote sound development of bone and muscle. However, individual differences in genetic makeup create such a degree in variation that general rate of gain recommendations are limited in scope and accuracy.
Individual differences are of primary importance when regulating feed intake.
Weanlings may consume 1.5 to 2.5 pounds of grain mix per 100 pounds of body weight per day. Yearlings may consume one to two pounds of grain mix per 100 pounds of body weight per day. These ranges assume the weanlings and yearlings are consuming hay at 0.75 to 1.0 pound per day per 100 pounds of body weight. Most weanling grain mixes contain between 1.2 and 1.4 Megacalories of digestible energy per pound. To ensure adequate intake of protein and minerals, Freeman said rations should contain about 14 percent crude protein, 0.6 percent calcium and 0.4 percent phosphorus.