Copper and lysine amino acid density responses in commercial broilers

Nutritional modulation of live performance and meat yield must be continuously tested as broiler strains become more efficient every year. This study evaluates both copper- and lysine-derived amino acid balance. In experiment 1, amino acid balance (high, moderate, and low) and copper (5 and 200 ppm) were investigated in a factorial array of treatments (6 treatments with 8 replications; 1,536 Cobb 500 male broilers across 48 floor pens from 1–40 d of age; 32 birds per pen). In experiment 2, amino acid density (high and low) was assessed in 2 broiler strains (a multipurpose and a high-yield strain) obtained from the field in a factorial array of treatments (4 treatments with 21 replications; 1,344 multipurpose and 1,344 high-yield broilers across 84 floor pens from 1–42 d of age; 32 birds per pen). Amino acid density treatments were created by altering digestible lysine and other essentials amino acids at a fixed ratio. Copper and amino acid density did not interact, but supplementing broilers with 200 ppm of copper in the form of tribasic copper chloride improved growth rate. Lysine-derived amino acid density improved performance and yields, but should be assessed as strains are improved for efficiency to ensure digestible lysine adequacy in the nutrient formulation matrix. Although both copper and lysine influence growth rate, interactive effects were not assessed in this study.