Vitamins A, D and E are the most common vitamins added to horse diets. Although B complex vitamins may not be commonly supplemented, including them in performance horse diets may be necessary.
· Vitamin A is the vitamin most likely to be marginal in most horse diets. The natural source of Vitamin A is beta-carotene which occurs in green forages and properly cured hays. As long as the hay source has a green colour and is leafy, then it will probably be more than adequate to meet the horse’s Vitamin A requirement.
· Vitamin D is very important in the normal absorption and utilization of calcium and phosphorus. It also functions in the absorption of several minerals for bone deposition. Natural sources of Vitamin D occur in sun-cured hay and cod liver oil.
· Vitamin E is found in ample quantities in most natural feedstuffs to meet the horse’s requirement. Roughages, cereal grains and especially cereal germ oils are high in Vitamin E, particularly wheat germ oil.
Biotin (vitamin H) is a popular nutritional supplement for horses to promote and maintain the growth of healthy hooves and coats. However, little up to date information is available whether supplementation of biotin has an actual effect.