Carcass characteristics of broilers at 42 days receiving diets with phytase in different energy and crude protein levels

Abstract

The aim of this study was to evaluate carcass characteristics and quality of breast meat after the inclusion of phytase in broiler diets with different levels of apparent metabolizable energy (AMEn) corrected for nitrogen and reduced crude protein (CP) supplemented with essential amino acids following the concept of ideal protein. A total of 1,500 Cobb broilers from 22 to 42 days (initial weight of 833 ± 7 g and final weight of 2741 ± 48 g) were distributed in completely randomized design in a factorial 3x3+1 experiment (three levels of AMEn - 2,950; 3,100 and 3,250 kcal/kg - and three levels of CP - 14, 16 and 18% - and an additional treatment - control without phytase, with 3,100 kcal/kg EMAn, 19.2% PB and 0.4% available phosphorus), in six replications of 25 birds each. At the end of the trial, two birds of each experimental unit were slaughtered in order to measure carcass yield and yields of parts and to determine the chemical composition of the breast meat. The levels of AMEn and CP of diets with phytase influenced (P<0.05) the carcass, breast and abdominal fat yield and humidity, protein and fat percentage in the pectoralis major muscle of the birds. The levels of 3,100 kcal AMEn/kg and 18% CP showed higher carcass and breast yield and lower abdominal fat deposition, although with higher fat percentage in the breast meat. It was concluded that the manipulation of the energy levels of diets with reduced crude protein supplemented with amino acids and phytase influenced the yields of parts of carcass and the breast meat quality of the broilers at 42 days.