The hoof is composed of living tissue that 93% protein. The quality and quantity of amino acids that the horse consumes will affect hoof growth and hardness. The primary protein in horse hoof is keratin which contains a large amount of the amino acid cystine. Cystine is in turn made of 2 cysteine (another type of amino acid) molecules that are connected by a disulfide (two sulfur atoms) bond. These disulfide bonds make the protein very tough and hard. You cannot feed cystine directly to the horse because it is indigestible. There is not an available commercial source of cysteine to add to rations. Instead, methionine is added to the diet, since it can be converted in the horse’s body to cysteine which is then used to produce cystine keratin in the hoof. A recent study from Germany (Coenen and Spitzlei, 1996) measured the amount of cystine in the hooves of 63 horses of a variety of breeds. They reported a linear relationship between hoof horn hardness and the percentage of cystine in the horses with good quality, intact hooves.
FOCUS HF provides methionine from both DL Methionine and zinc methionine. Both are high bioavailable and well utilized by the equine. Please see SOURCE Products: for Horses, for more information.