Effects of exogenous xylanase supplementation in plant-based diets on growth performance, nutrient digestibility and digestive enzyme activities of juvenile mori (Cirrhinus mrigala)

The present experimental study was conducted to determine the effects of xylanase supplementation on growth performance, nutrient digestibility and digestive enzyme activities of mori, Cirrhinus mrigala. Mori with an initial body weight of 8.34 ± 0.23 g were fed seven experimental diets: a diet with high fish meal content (positive control, PC), a diet with high plant content (negative control, NC), and five other diets with increasing levels of xylanase (680, 1273, 1882, 2486 and 3091 U/kg). Each diet was fed to triplicate groups of 15 fish each for 60 days. After the trial termination, supplementation of xylanase significantly improved final weight (FW), weight gain (WG) and specific growth rate (SGR) compared to NC diet. The best feed conversion ratio (FCR) was observed at 1882 U/kg of xylanase supplementation level which was non-significant (P > 0.05) to PC diet (high fish meal content). Whole body proximate composition and apparent digestibility coefficient (ADC%) for dry matter (DM), crude protein (CP), crude fat (CF), crude ash (CA) and gross energy (GE) were significantly affected by xylanase supplementation. Activities of hepatopancreatic and intestinal amylase, protease and lipase showed an increasing trend with the increase in xylanase supplementation level, peaking at 1882 U/kg of xylanase (non-significant (P > 0.05) to PC diet) and declining thereafter (2486 U/kg-3091 U/kg). Quadratic regression analysis showed that 1948 U/kg of xylanase was the optimum value for supplementation of xylanase in plant-based diet. In conclusion, exogenous xylanase supplementation improved the growth performance, nutrient digestibility and digestive enzyme activities in juvenile mori fed plant-based diet.