Effect of dietary supplementation of β-mannanase on growth performance, carcass characteristics, excreta microflora, blood constituents, and nutrient ileal digestibility in broiler chickens

Abstract

Objective: The aim of the present study was to investigate the effects of dietary supplementation of βmannanase on growth performance, carcass characteristics, excreta microflora, blood constituents, and nutrient digestibility in broiler chickens. Methods: A total of 680 onedold Ross 308 (as hatched) broiler chickens were used in a 35d growth assay. Chicks were sorted into pens with 17 birds/pen and 10 pens/treatment. Treatment diets were contained either 44% or 48% crude protein (CP) soybean meal (SBM) with or without βmannanase. Results: Using SBM containing 48% CP led to an improvement (p<0.05) in feed conversion ratio (FCR) from d 1 to 14. Addition of βmannanase to the diets significantly improved body weight gain (BWG) and FCR from d 1 to 14. During overall experimental period, BWG was affected (p<0.05) by CP level of SBM and inclusion of βmannanase, but FCR and feed intake were not affected. Carcass characteristics were not influenced by treatment diets. The results showed that digestibility of dry matter (DM), nitrogen (N), and energy was not affected by CP level of SBM and/or inclusion of βmannanase. Among essential amino acids (EAA) apparent digestibility of valine, methionine, and leucine improved (p<0.05) by the addition of βmannanase to the diets. The results demonstrated that ileal digestibility of DM, N, and energy was not affected by treatment diets. Among EAA, the ileal digestibility of valine and arginine was higher (p<0.05) in the diets containing 48% CP SBM and/or βmannanase. Excreta Lactobacillus count increased (p<0.05) by the addition of βmannanase to the diets. Blood urea nitrogen, creatinine, and total protein level were not affected by treatments. Conclusion: Feeding chickens with diets containing 44% CP SBM resulted in detrimental effects on growth performance and digestibility of nutrients, but addition of βmannanase to the 44% CP diet improved the growth performance of chickens without any effects on carcass characteristics.