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, T
hreonine is the third most limiting amino acid in broiler diets behind the
total sulphur-containing amino acids and lysine. Research into the threonin
e requirement of broilers is sparse compared with that of methionine and ly
sine. 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. T
his review summarises this recent research. It also considers threonine nee
ds for optimal immune system functions, feather growth, glycine requirement
s and gastrointestinal functions, as well as under conditions causing heat
stress.