Avaliação da correção da energia metabolizável pelo balanço de nitrogênio em alimentos para frangos de corte

Abstract

In order to determine apparent metabolizable energy (AME) and apparent metabolizable energy corrected by nitrogen balance (AMEn) of feed ingredients and to evaluate the effects of this correction on performance (zoothecnical and economic) and carcass yield of broiler chickens, two experiments were conducted: I) AME and AMEn determination of corn, soybean meal, meat and bone meal, poultry byproducts meal and feather meal by total excreta collection method at 7-10 days and 26-29 days old, 450 Cobb male chicks were randomly distributed in 30 cages, with six treatments and five replications; II) performance, carcass yield and economic evaluation of broilers, distributed in a completely randomized desing, with five treatments (nutritional plans) and six replications of 32 birds each. The results were subjected to analysis of variance and the differences were compared by Tukey test. There were differences between AME and AMEn values for early and growth collections period for all feed ingredients studied. The AME and AMEn of corn, soybean meal and feather meal were lower when determined in younger birds, as well as the difference between AME and AMEn. Birds that received treatments A (AMEn from Rostagno et al., 2011) and E (AME adjusted by age) showed better performance with the best feed cost, and the treatment E had smaller feed convertion ratio. Therefore, the use of formulations based on metabolizable energy adjusted for age and without correction by nitrogen balance is feasible, both from zoothecnical and economic point of view. There was no difference in carcass yield and parts between the assessed nutritional plans.