Amino acid supplementation of low-protein broiler diets: 2. Formulation onan ideal amino acid basis

In order to apply the ideal amino acid concept to broiler production, more knowledge is needed concerning low crude protein (CP), amino acid-supplemen ted diets. Three experiments were conducted to evaluate performance, carcas s traits, and nitrogen balance of broilers fed low-CP diets supplemented wi th amino acids according to an ideal amino acid ratio. Marginal reductions in CP in both experiments resulted in equal body weight (BW) gain and conve rsion compared to birds fed the control diet, regardless of the supplementa tion. In contrast, severs CP reduction in both experiments resulted in a si gnificant depression in BW gain and feed:gain. Although amino acid suppleme ntation corrected the depression in BW gain and feed conversion in Experime nt 1, it did not restore feed conversion in Experiment 2. A small reduction in dietary CP, without amino acid supplementation, demonstrated inconsista nt responses. Breast meat yield was unaffected by the further reduction in dietary CP, regardless of amino acid suppplementation. Nitrogen excretion w as dramatically reduced by a reduction in dietary CP 1.2 percentage units, but unexpectedly not when dietary CP was reduced by 2.7 percentage units.