低鱼粉饲料中添加外源酶制剂对大口黑鲈生长性能、体组成以及饲料利用率的影响

本实验旨在探究低鱼粉饲料中添加外源酶制剂对大口黑鲈（Micropterus salmoides）生长性能、体组成以及饲料利用率的影响。以25%鱼粉组为对照组，在此基础上分别添加中性蛋白酶、角蛋白酶、纤维素酶、植酸酶以及复合酶（中性蛋白酶、角蛋白酶、纤维素酶和植酸酶）配置6组等氮等脂的实验饲料。以初始体重为（39.65±0.15）g的大口黑鲈为实验对象，进行了57d的养殖实验，每天饱食投喂2次。结果显示，角蛋白酶、纤维素酶和复合酶的添加显著提高了大口黑鲈的末体重、增重率以及特定生长率（P < 0.05）；中性蛋白酶、角蛋白酶和植酸酶的添加显著提高了大口黑鲈的蛋白沉积率（P < 0.05）；而植酸酶和复合酶的添加对脂肪沉积率的提升明显（P < 0.05）；不同酶制剂的添加均对饲料中蛋白质和脂肪表观消化率有改善作用：复合酶组的蛋白质表观消化率最高，且显著高于其他处理组（P < 0.05）；角蛋白、纤维素酶和复合酶组的脂肪表观消化率显著高于中性蛋白酶和对照组组（P < 0.05）。综上，在高植物蛋白饲料中添加一定比例的酶制剂，特别是角蛋白酶、纤维素酶或复合酶，可以有效地促进其对营养物质的消化和吸收，进而改善饲料利用率，提高大口黑鲈的生长性能。

Effects of dietary exogenous enzymes on improving growth performance, body composition and feed utilization of largemouth bass (Micropterus salmoides) fed low fishmeal-based diet

This study was conducted to evaluate the effects of exogenous enzymes inclusion on growth performance, body composition and feed efficiency of largemouth bass. The diet with 25% fish meal was considered as the control, and another five isonitrogenous and isolipidic diets were formulated with the inclusion of neutral protease, keratinase, cellulase, phytase and complex enzymes (neutral protease, keratinase, cellulase and phytase), respectively. The fish were fed the experimental diets for 57 days twice daily. Results showed that fish fed the diet with keratinase, cellulase or complex enzymes inclusion displayed higher final body weight, weight gain rate and specific growth rate compare to the control group. Meanwhile, largemouth bass fed the diet with the supplementation of neutral protease, keratinase or phytase obtained significantly higher protein retention rate than that in the control group. The lipid retention rate was significantly higher in largemouth bass fed the diet with phytase or complex enzyme compare to other groups. The inclusion of exogenous enzyme significantly elevated the nutrient apparent digestibility coefficient of largemouth bass: the highest apparent digestibility of protein was observed in largemouth bass fed the diet with complex enzyme, which was significantly higher than other groups; the apparent digestibility of lipid in largemouth bass fed the diet with keratin, cellulase and complex enzyme than that in the neutral protease and control group. In summary, the supplementation of exogenous enzymes, especially keratinase, cellulase and complex enzyme, in high plant protein diet, can effectively promote the digestion and absorption of nutrients, improve feed utilization and elevate growth performance of largemouth bass.