Responses of Cobb x Cobb 500 slow feathering broilers to feeding programs with increasing amino acid densities.

摘要

An evaluation of the effects of feeding programs with three amino acid (AA) densities given to males and females from a fast growth broiler breed was conducted. A total of 1200 Cobb x Cobb 500 broilers were distributed across 6 treatments in a 2 x 3 factorial arrangement (Sex x AA Density) with 8 replications of 25 birds per pen. Maize-soybean meal, provided from 1 to 7, 8 to 21, 22 to 35 and 36 to 42 d of age, was formulated without crude protein restriction maintaining minimum ratios between essential AA and Lysine (Lys) in a true digestible (dig) basis as follows: total sulfur AA, 0.75; threonine, 0.65, valine, 0.75 (from 1 to 21 d) and 0.78 (from 22 to 42 d). Experimental treatments were Low (L), Moderate (M) and High (H) AA density diets with M having dig Lys of 1.25, 1.19, 1.09 and 1.05% in the pre-starter to withdrawal phases, respectively. Diets L and H had reductions and increases of 12% dig Lys in relation to the Moderate diet. There were no effects of treatments on mortality (P