Limiting Amino Acids in Low Crude Protein Broiler Diets

Research was conducted to determine the level of l-Lysine that can be included in corn-soybean meal (C-SBM) diets for broilers before an amino acid other than methionine, lysine, threonine or glycine becomes limiting and to determine the order of limiting amino acids in low crude protein C-SBM diets. All experiments were conducted with Ross 708 broilers (0 to 18 d of age) in brooder batteries. Treatments contained 7 or 8 replicates with 6 birds per replicate. In all experiments, a control C-SBM diet containing no l-Lys.HCl and a positive control diet with supplemental glycine to provide 2.32% total dietary glycine plus serine were fed. All diets were formulated to contain 1.26% total lysine. All diets with added l-Lys.HCl contained supplemental glycine to provide 2.32% total dietary glycine plus serine.
In a series of five studies, the researchers systematically determined the limiting amino acids in a C-SBM based broiler diet. They found that up to 0.25% l-Lys.HCl could be added to C-SBM diets supplemented with methionine, threonine and glycine with no negative effects on average daily gain, average daily feed intake or feed utilization efficiency. They further found that arginine and valine are equally limiting after the bird's lysine, methionine, threonine and glycine needs are met. (Comment-Bottom line is that reducing crude protein levels in broiler diets requires greater attention to amino acid levels and balance).

In a series of five studies, the researchers systematically determined the limiting amino acids in a C-SBM based broiler diet. They found that up to 0.25% l-Lys.HCl could be added to C-SBM diets supplemented with methionine, threonine and glycine with no negative effects on average daily gain, average daily feed intake or feed utilization efficiency. They further found that arginine and valine are equally limiting after the bird's lysine, methionine, threonine and glycine needs are met. (Comment-Bottom line is that reducing crude protein levels in broiler diets requires greater attention to amino acid levels and balance).

Waguespack, A.M. and co-workers. 2009. Effect of incremental levels of L-lysine and determination of the limiting amino acids in low crude protein corn-soybean meal diets for broilers. Poultry Sci. 88(6):1216-1226.