Formulating rations for horses may be accomplished by some rather basic mathematical calculations or by a series of complex procedures to formulate least-cost rations by computer. The most accurate method would be to consider the requirements for all nutrients--protein, energy, minerals and vitamins--in making the calculations. In practice, however, it usually is not necessary to be concerned with calculations of exact needs of all individual minerals and vitamins, since adequate amounts of trace minerals commonly are assured through inclusion of a trace mineralized salt in the ration. Other nutrients, such as the B vitamins, often are present in natural feedstuffs, or may be synthesized by bacteria present in the intestinal tract of the horse. The nutrients of major concern in horse ration formulation are energy, protein, calcium, phosphorus and vitamin A.
Wood, Craig H.; Jackson, Stephen; and Baker, John P., "Formulating Rations for Horses" (1988). Agriculture and Natural Resources Publications. Paper 8.