China H&Z® L-Tryptophan is an important precursor for the biosynthesis of auxin in plants. Amino acids medicine and important nutrient. It can participate in the renewal of plasma protein in animal body, and promote riboflavin to play a role, also contribute to the synthesis of niacin and heme, can significantly increase the antibodies in pregnant animal foetus, and can promote lactation of lactating cows and sows. When livestock and poultry lack tryptophan, growth is stunted, weight is lost, fat accumulation is reduced, and testicular atrophy occurs in breeding males. It is used in medicine as a control agent against scurvy.