Amino acid supplementation of low-protein broiler diets: 1. Glutamic acid and indispensable amino acid supplementation

To maintain optimal growth anf 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 dis pensable amino acid nitrogen in poultry by evaluating the effects of lower levels of CP along with amino acid supplementation on broiler performance a nd carcass development. Lowering dietary CP without amino acid suppplementa tion reduced body weight (BW) gain and increased feed:gain ratio. Supplemen tation of glutamic acid (Glu) had no effect on feed conversion, but appeare d to decrease feed intake and BW gain. Supplementation of indispensable ami no 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 wit h Glu, resulted in reduced carcass yield, increased percentage abdominal fa t, and breast meat yields similar to those of birds fed the positive contro l. This research demonstrates the importance of IDAA in low-CP broiler diet s, but failed to show an advantage to Glu supplementation as a dispensable amino acid nitrogen source.