Exogenous protease supplementation of poultry by‐product meal‐based diets for broilers: Effects on growth, carcass characteristics and nutrient digestibility

Summary An experiment was conducted to investigate the effects of three levels (0%, 3% and 6%) of poultry by‐product meal ( PBM ) with or without protease on broiler growth, carcass characteristics and nutrient digestibility from 1 to 35 days. Two hundred and forty birds ( n = 240) were fed equi‐caloric and equi‐nitrogenous ( ME 2850 kcal/kg; CP 20%) diets throughout the experiment. The enzyme supplementation increased feed intake ( p < .01) and body weight gain ( p < .01), but feed:gain remained unaffected ( p > .05) from 1 to 21 days. Increasing level of PBM decreased feed intake ( p < .05), but body weight gain was improved ( p < .05) at 3% PBM level during 1 to 21 days. The feed:gain was improved ( p < .05) in birds fed diets containing 3% PBM . The feed:gain was also improved in birds fed diets containing 3% PBM from 1 to 35 days. However, feed intake and body weight gain in birds fed diets containing PBM remained unaffected. An interaction ( p < .01) on feed intake between enzyme and PBM was noticed during 1 to 21 days. However, no interaction was recorded for body weight gain and feed:gain. The per cent carcass yield improved ( p < .01) in birds fed diets supplemented with enzyme. The per cent breast meat yield was depressed ( p < .005) in birds fed diets containing PBM . Apparent metabolizable energy ( p < .001), nitrogen retention ( p < .01), apparent metabolizable energy corrected for nitrogen ( p < .001), and apparent digestibility coefficient for nitrogen ( p < .01) improved in birds fed diets containing enzyme; however, a reverse was noticed in those fed diets containing only PBM . In conclusion, inclusion of 3% PBM along with supplementation of exogenous protease improved performance and nutrient digestibility in broilers.