Threonine was discovered in fibrin hydrolysate in 1935 and proved to be the last essential amino acid to be discovered. Threonine is mainly used in medicine, chemical reagents, food fortification, and feed additives. We mainly describe its function as a feed additive, which is often added to the feed of immature piglets and poultry, and is the second limiting amino acid in pig feed and the third limiting amino acid in poultry feed.
Threonine is the main component of small intestine mucus protein, which is essential in the synthesis of glycoprotein on the surface of pig small intestine, and has an important role in maintaining intestinal health and intestinal mucosa function of pigs, especially suckling piglets. The addition of synthetic amino acids to low-protein diets reduces the crude protein content of the diet, which is economical and has no adverse effect on animal performance. It is especially important for early weaned piglets, because piglets' digestive system is not fully developed, and high protein content in the diet can easily induce nutritional dysentery. Threonine production plays an important role in piglets.
Threonine has a certain regulating effect on feed intake. Feed intake and daily weight gain increase with the increase of threonine level; when it exceeds a certain requirement, feed intake and daily weight gain decrease with the increase of threonine level, that is, too much or too little threonine will reduce feed intake and daily weight gain.
Adding threonine to feed can reduce the nitrogen content in manure and urine of livestock and poultry, and the concentration and release rate of ammonia in livestock and poultry houses.
Adding threonine to the diet of laying hens can significantly improve the egg production and feed conversion rate. When threonine protein is added to the diet of broilers, it can significantly improve its daily weight gain and feed conversion rate.
In the immune system of the body, antibodies and immunoglobulins are all proteins, and the lack of threonine protein will inhibit the production of immunoglobulins and T and B lymphocytes and affect the immune function. Threonine is the main limiting amino acid in the immunoglobulin molecule of poultry, adding threonine can improve the immune function of the body.