Mad Barn Lysine99% pure crystalline form of the amino acid lysine that can be used to support healthy joints in exercising and aging horses Growing horses might also benefit from supplemental lysine to support bone growth Horses that have poor hoof growth, poor coat quality, or loos of muscle mass might be affected by a protein deficiency in their diet Low milk production in lactating mares and flagging stamina might also be signs of deficiency Lysine is considered