M.A.S.S. Builder® is designed to help maintain healthy weight by combining L-Lysine, Threonine and Fenugreek for maximum efficacy. This unique formula is a non-steroidal product that is veterinarian recommended to help maintain healthy weight and lean muscle development in the horse. M.A.S.S. is the only supplement of this type to include Fenugreek, a natural and effective substance that enhances the appetite in horses.