Protein requirements and carcass composition of male broiler breeders from 27 to 61 weeks of age

Two trials were carried to estimate the protein requirements and carcass composition of male broiler breeders front 27 to 61 weeks of age. Four hundred and fifty females and 75 males of Cobb-500 strain were selected to evaluate the body weight. semen volume. spermatic concentiation, mobility, vigor and fertility of spermatozoa. Thirty males were used for evaluation of carcass chemical composition (DM CP and crude fat [CF]) as a function of protein intake. The experiment was analyzed as a complete randomized design with five treatments (12.0, 14.2, 16.4. 18.6, and 20.8 g CP/bird/ day). In the first trial (reproductive performance evaluation). each treatment was composed by 15 replicates of one rooster and in the second trial (carcass evaluation). each treatment consisted of two replicates of three roosters (three were slaughtered at 45 weeks and three at 61 weeks of age). Quadract effect of CP intake on semen volume, spermatic concentration. motility, sperniatozoa vigor and fertility was observed. Only body weight and DM percentage were not affected by treatments. However, at extreme levels (deficiency or excess) of protein intake, CF percentage in the carcass increased and the reproductive performance decreased. Therefore. tire intake of 16.9 g of CP/rooster/day is recommended to meet CP requirements of male broiler breeders from 27 to 61 weeks of age.