Effect of β-mannanase and protease in corn-soya based diets on broiler performance

The effect of β-mannanase and protease supplementation was assessed in broiler fed energy basal diets with low energy (energy basal) (2775 kcal ME/kg in starter and 2975 kcal ME/kg in finisher) and low protein (protein basal) (20.0 and 17.0% CP), respectively. These diets were compared with normal energy (2900 kcal ME/kg in starter and 3100 kcal ME/kg in finisher) and protein diet (22.0 and 19.0% CP) by allotting these diets randomly to broilers (1–42 d). The live weight gain of chicks was comparable among enzyme supplemented and unsupplemented groups at both 21 and 42 d of age. But a trend of higher gain was observed at 42 d with enzyme -mannanase supplementation (280 IU/kg). The live weight gain was 1.39% higher with enzyme supplemented compared to energy basal group. Protease supplementation (4000, 8000 IU/kg) to protein basal diet had no significant effect on the body weights during the entire experimental period. The feed conversion ratio (FCR) was lower (P<0.05) in energy basal group compared to positive control and supplementation of βmannanase improved the FCR in birds at 21 d of age and was comparable to positive control. However, protease did not influence the feed efficiency of protein basal diet. The in vitro release of sugars in enzyme supplemented and unsupplemented diets showed that enzyme supplementation was effective in enhancing the digestibility of nutrients. The in vitro sugar release with β-mannanase supplementation to energy basal diet was 214 mg/g and 185 mg/g in starter and finisher diets, respectively compared to the energy basal diet (187 mg/g and 167 mg/g). But there was no significant difference in the total sugars released due to protease supplementation. The results indicated that βmannanase supplementation to low energy diet enhanced the performance of broilers, while protease supplementation to low protein cornsoya diets was not effective in broilers.