Many factors influence hoof growth and health, but proper nutrition is among the most important. Protein and amino-acid intake and metabolism are key; minerals such as zinc and calcium, and vitamins such as biotin and vitamin A are also essential.
Critical too, however, is overall energy intake—in other words, the amount of calories your horse gets in relation to the amount of work he’s doing. A horse in “negative energy balance” will make use of the protein in his diet or from within his body to make up energy needs for maintenance or growth. This may create a secondary protein or amino-acid deficiency, which can impede hoof growth.
Check with your veterinarian or equine nutritionist to make sure your horse is getting the right amount of proper nutrients for his needs.
Source: Kentucky Equine Research