Effects of dietary protein level on protein deposition in broilers: 1. Productive performance and carcass characteristics

Abstract

The aim of study was to evaluate the influence of different levels of dietary protein on broiler performance and carcass characteristics from 1-42 days. One-day-old unsexed Cobb 500 broilers (n=600) were randomly assigned in 3 groups with 4 replications per treatment. The diets were formulated to contain 3 levels of protein: high protein (HP), medium protein (MP) and low protein (LP). The diets were isocaloric, with similar content of digestible sulphur amino acids, lysine, calcium and available phosphorus. In overall periods weight gain (WG) in the HP diet was higher with 4.28% and in the LP diet were lower by 4.44% vs. MP (P<0.0001). Feed conversion ratio (FCR) in overall period in the HP diet was reduced with 3.96% and in the LP diet was increased with 4.95% vs. MP (P<0.002). The feed intake (FI) was not influenced by the dietary protein level during overall period. Carcass yield and the percentage of broilers liver were not affected by the dietary protein level. Breast and legs yield were influenced by the dietary protein level, in LP diet was observed a decrease with 4.10% (P<0.04), respectively 4.47% (P<0.0001) vs. MP diet. The HP diet produced carcasses that contained lower levels (2.49%; P<0.0001) of abdominal fat than the LP diet (2.78%; P<0.0001). We concluded that the dietary protein level influences significantly the performance (weight gain, feed conversion ratio) and carcass parameters (breast and legs yield, abdominal fat) of broilers.