Vita Flex Pure Lysine, 151 Day Supply, 4 lbs Lysine is recommended for equine diets low in alfalfa, clover and soy to improve the availability of protein in the diet Lysine is the first limiting amino acid in the diet of growing foals National Research Council.Lysine helps increase growth and development The protein component most often lacking in horses diets, in its most pure and economical form An essential amino acid 448 day supply, 4 pounds