Are you providing enough? Today’s horse owners are no doubt aware of the importance of vitamins in the diets of their horses, but many may not be aware of the role vitamins play in equine nutrition. Vitamins in their fresh natural form are organic substances found in grains and forages. They are important as cofactors, or facilitators, for different metabolic function, and deficiencies of them can cause disease conditions. Vitamins, unlike many of the nutrients we feed our horses, cannot be broken down for energy, and they provide no other nutrients to the horse.