Effects of dietary amino acid density regimens on growth performance and meat yield of Cobb × Cobb 700 broilers

Abstract

The effects of dietary amino acid (AA) density on the performance and meat yield of Cobb × Cobb 700 broilers were evaluated in the current study. Cobb × Cobb 700 chicks, obtained from commercial hatchery, were fed either moderate- or high-AA-density diets within the starter (0 to 14 d, in crumbles), grower (14 to 28 d, in pellets), finisher (28 to 35 d, in pellets), and withdrawal (35 to 56 d, in pellets) phases of a grow-out program, for a total of 8 possible treatment combinations. Cobb × Cobb 500 birds, also from a commercial hatchery, were fed a moderate-AA-density diet and served as a reference. Before formulation of the experimental diets, the corn, soybean meal, and animal byproduct ingredients in the feed were analyzed for total AA concentration. At 42 and 56 d of age, live performance, meat yield, and feed cost efficiency were evaluated. Mortality, which averaged approximately 3%, was not affected by any treatments. Body weight on d 42 and 56 were not affected by AA density in the diets. Based on main effects of FCR, Cobb × Cobb 700 birds benefited greatly from being fed high-AA-density diets during the finisher and withdrawal feeding phases. Feeding Cobb × Cobb 700 moderate- AA-density diets throughout all feeding phases proved to be more economically efficient when compared with feeding high-AA-density diets at an early stage and a moderate-AA-density diet at a later stage. This is based on a lower feed cost to cut-up part value ratio observed on d 56. Although live performance and meat yield of Cobb × Cobb 700 broilers responded to high-AAdensity diets, this diet did not result in the most cost-effective program. © 2013 Poultry Science Association, Inc.