Nutritional considerations concerning threonine in broilers

An important objective of the least cost formulation of broiler diets is to provide sufficient amounts of the most limiting amino acids to support the needs of tissue maintenance and accretion while minimising any excesses, Threonine is the third most limiting amino acid in broiler diets behind the total sulphur-containing amino acids and lysine. Research into the threonine requirement of broilers is sparse compared with that of methionine and lysine. However, recent work on the threonine needs of growing and finishing broilers has been invaluable in helping commercial nutritionists determine the minimum amount of threonine required in least cost diet formulations. This review summarises this recent research. It also considers threonine needs for optimal immune system functions, feather growth, glycine requirements and gastrointestinal functions, as well as under conditions causing heat stress.