L-Threonine plays an important role in processes of maintenance and, more particularly of digestion. In practice, L-Threonine is the second limiting amino acid in feed for pigs and the third limiting amino acid in feed for poultry.L-Threonine is an essential amino acid. It is involved in the synthesis of mucin, a protein supporting intestinal function and integrity. L-threonine has a role in the immune system, in O-linked glycosylation, protein phosphorylation and glycine synthesis.L-threonine has been used for the selection of transformed cells. It has also been used to study the effects of amino acids in promoting food consumption in Drosophila melanogaster.