Effect of microbial proteases on the performance and carcass traits in commercial broilers fed maize-soy bean meal -meat cum bone meal based diets

An experiment was conducted to evaluate the effective combinations of proteases (acid, neutral and alkaline) and their concentrations on performance and carcass traits in commercial broilers fed on diets containing sub-optimal protein levels. A total of 320 broilers were used in completely randomized design with eight treatments with eight replicates in each treatment and 5chicks in each replicate. Maize-soybean meal (CD) and maize-soybean-meat cum bone meal (BD) based diets were formulated to contain 23, 21 and 19.5% crude protein (CP) and 19.5,18 and 17.5% CP, respectively during pre-starter (1-11 d), starter (12-28d) and finisher (29-42d) phases. All the diets were fed adlibitum from 1d to 42 d of age. The low protein BD were supplemented with two different combinations of proteases (1:1:1 and 2:1:1 acidic, neutral and alkaline proteases, respectively) with total activity of 2000, 4000 and 6000u/kg.The results revealed that the broilers fed CD had significantly higher body weight gain compared to those fed BD. Supplementation of proteases to the BD significantly (P < 0.05) improved the body weight gain and feed efficiency during 21 d of age, but not during the latter phase ( 42 d of age) of growth. The broilers fed on CD had significantly (P < 0.05) higher ready to cook and breast yields compared to those fed the BD or BD with protease supplementation. The relative weight of abdominal fat was significantly (P < 0.05) reduced in broilers fed BD with 1:1:1 (acidic, neutral and alkaline proteases) at 4000 u protease / kg diet as compared to BD. It is suggested that addition of proteases to low protein diets had a significant positive effect in young chicken fed on maize-soybean meal and -meat and bone meal based diets.