Effects of dietary protein level on protein deposition in broilers: 2. Body composition, plasma metabolic profile and litter composition
The aim of study was to evaluate the effects of three dietary protein levels on body composition, plasma metabolic profile and litter composition of broilers at 42 days of age. One-day-old unsexed Cobb 500 broilers (n=600) were randomly assigned in 3 groups with 4 replications per treatment. Three diets were formulated for each growth phases, 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. The empty body weight (BW) of broilers was influenced by the dietary treatments (+ 8% in HP, respectively - 7.7% in LP vs. MP; P<0.001). The carcass fraction in the HP diet represented 86.97% of BW and in the LP diet 85.47% of BW vs. MP (85.79% of BW; P<0.028). Also, the organ fraction was influenced by the dietary protein level in HP diet represented 10.52% of BW and in the LP 11.73% of BW vs. MP (11.42%; P<0.041). The chemical composition of carcass, organ and feathers fraction was not affected by the dietary treatments (P>0.05). In general, plasma biochemical parameters were not influenced by the dietary protein levels (P>0.05). In conclusion, low protein diets can support similar quality performance that high or medium diets when the quality ingredients are used. The lower dietary protein level resulted in reduced nitrogen excretion, which is an important advantage for environmental safety.
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