Amino Acid Supplementation of Low-Protein Broiler Diets: 2. Formulation on an Ideal Amino Acid Basis

Abstract

In order to apply the ideal amino acid concept to broiler production, more knowledge is needed concerning low crude protein (CP), amino acid-supplemented diets. Three experiments were conducted to evaluate performance, carcass traits, and nitrogen balance of broilers fed low-CP diets supplemented with amino acids according to an ideal amino acid ratio. Marginal reductions in CP in both experiments resulted in equal body weight (BW) gain and feed conversion compared to birds fed the control diet, regardless of Thr supplementation. In contrast, severe CP reduction in both experiments resulted in a significant depression in BW gain and feed:gain. Although amino acid supplementation corrected the depression in BW gain and feed conversion in Experiment 1, it did not restore feed conversion in Experiment 2. A small reduction in dietary CP had little effect on carcass fat or lean yields, while further reductions in dietary CP, without amino acid supplementation, demonstrated inconsistent responses. Breast meat yield was unaffected by the further reduction in dietary CP, regardless of amino acid supplementation. Nitrogen excretion was dramatically reduced by a reduction in dietary CP by 1.2 percentage units but unexpectedly not when dietary CP was reduced by 2.7 percentage units.