Amino Acid Supplementation of Low-Protein Broiler Diets: 1. Glutamic Acid and Indispensable Amino Acid Supplementation

Abstract To maintain optimal growth and carcass development, nutritionists commonly fortify diets low in crude protein (CP) with crystalline amino acids. This experiment sought to apply the ideal amino acid concept and the need of dispensable amino acid nitrogen in poultry by evaluating the effects of lower levels of CP along with amino acid supplementation on broiler performance and carcass development. Lowering dietary CP without amino acid supplementation reduced body weight (BW) gain and increased feed:gain ratio. Supplementation of glutamic acid (Glu) had no effect on feed conversion, but appeared to decrease feed intake and BW gain. Supplementation of indispensable amino acids (IDAA) in addition to Glu to the reduced CP diets improved BW gain and feed:gain ratio, but failed to improve performance to a level achieved by birds fed the positive control diet. Lowering dietary CP, without or with Glu, resulted in reduced carcass yield, increased percentage abdominal fat, and reduced breast meat yield. Birds fed diets supplemented with IDAA + Glu had carcass yields, percentage abdominal fat, and breast meat yields similar to those of birds fed the positive control. This research demonstrates the importance of IDAA in low-CP broilers diets, but failed to show an advantage to Glu supplementation as a dispensable amino acid nitrogen source.