A metabolism trial was carried out in metabolic cages in a completely randomized experimental design to evaluate the effect of CP reduction on nutrients and energy digestibility in the diets of broiler chickens. A hundred sixty male broiler chickens were randomly allotted to four treatments (CP levels) and four replicates of 10 birds each. The crude protein levels used in the diets were 21, 19, 17 and 15. The total excreta was colleted and recorded from 25 to 29 days of age. The CP reduction improved dry matter and energy digestibility linearly. A quadratic effect of the CP level on CP digestibility was observed. The maximum digestibility was estimated for broilers fed 15.3% CP diets. The nitrogen intake and excretion decreased linearly with the CP reduction. The maximum retained nitrogen and nitrogen efficiency utilization were estimated for broilers fed 18.3 and 15.3% CP diets, respectively. No effect of CP levels on ME was observed.
digestibility; protein; energy; nitrogen; broiler chicken
