... , and tryptophan as to restore the body fatigue , and promote the growth and development results . Medicine , due to feed-grade L - ... composite 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 . ...