... promote the growth and development results . Medicine , due to feed-grade L - threonine structure containing hydroxyl groups on the human skin ... amino acid infusion . At the same time , feed-grade L-threonine is to create a class of high efficiency ... aquaculture , feed-grade L-threonine as a feed amino acids, widely used to add the piglet feed , pig feed, chicken feed , shrimp feed and eel feed . ...