饲料中添加枯草芽孢杆菌对青鱼生长、消化酶活性和鱼体组成的影响

用不加枯草芽孢杆菌的对照饲料和分别添加2×10⁶、2×10⁷、2×10⁸和5×10⁸ cfu/g枯草芽孢杆菌的4种实验饲料, 分别喂养初始均重为(4.16±0.03) g的5组三重复的青鱼鱼种8周。饲养试验在15只容积为80 L循环式水簇箱内进行, 水温控制为(25±0.5) ℃。结果表明: 饲料中添加枯草芽孢杆菌的实验组青鱼鱼体终重和鱼体增重比不添加的饲料组显著提高, 而饲料系数则显著降低(P<0.05), 不同枯草芽孢杆菌添加量对青鱼鱼体增重和饲料系数均无显著影响(P>0.05)。饲料中添加枯草芽孢杆菌对青鱼的成活率无显著影响(P>0.05)。青鱼摄食添加枯草芽孢杆菌的实验饲料后其肠蛋白酶活性比不添加组显著升高(P<0.05), 并随着枯草芽孢杆菌添加量的增加而显著上升(P<0.05), 但添加量到2×10⁷ cfu/g后继续增加则不再显著变化(P>0.05)。青鱼摄食添加枯草芽孢杆菌的实验饲料后, 其肠淀粉酶活性均比不添加组显著升高(P<0.05), 且随枯草芽孢杆菌添加量增大呈不断升高的趋势。青鱼摄食添加2×10⁷、2×10⁸和5×10⁸ cfu/g枯草芽孢杆菌的饲料后, 其肝胰脏蛋白酶活性显著高于摄食不添加或添加2×10⁶ cfu/g枯草芽孢杆菌的实验组(P<0.05)。青鱼摄食添加枯草芽孢杆菌的实验饲料后, 其肝胰脏淀粉酶、肝胰脏脂肪酶和肠脂肪酶的活性均与不添加的实验组无显著差异(P>0.05)。青鱼鱼种摄食添加枯草芽孢杆菌的饲料与摄食不添加枯草芽孢杆菌的饲料相比, 其全鱼营养组成均无显著差异(P>0.05)。因此, 在实验条件下, 饲料中添加2×10⁶—5×10⁸ cfu/g的枯草芽孢杆菌能促进青鱼鱼种的生长和降低饲料系数, 而对鱼体组成没有影响。

EFFECT OF ADDING BACILLUS SUBTILIS TO DIETS ON GROWTH PERFORMANCE,DIGESTIVE ENZYMES ACTIVITY AND BODY COMPOSITION OF FINGERLING BLACK CARP (MYLOPHARYNGODON PICEUS)

A basal diet without adding Bacillus subtilis and four test diets containing 2×10⁶, 2×10⁷, 2×10⁸ and 5×10⁸ cfu/g of the B. subtilis were prepared to feed five groups of fish in triplicate with an initial average body weight of (4.16±0.03) g respectively. The feeding experiment was conducted in 15 re-circulating tank systems (80 L each) at a controlled water temperature of (25±0.5)℃ for eight weeks. The results showed that the weight gain of fish fed diets with B. subtilis increased significantly compared to that of fish fed the basal diet (P<0.05), and the feed conversion ratio(FCR) reduced significantly (P<0.05). However, weight gains and FCR of fish fed diets containing different levels of B. subtilis showed no significant difference (P>0.05). Survival rates were not affected by adding B. subtilis to diets (P>0.05). Intestine protease activities of fish fed diets with B. subtilis were higher than that of fish fed the basal diet (P<0.05), and intestine protease activity increased with the increasing level of B. subtilis supplement up to 2×10⁷ cfu/g, but above this level, it appeared to keep stable. The intestine amylase activity of fish fed diets with B. subtilis increased significantly (P<0.05), and higher level of B. subtilis supplementing appeared to have higher activity. Fish fed diets with 2×10⁷, 2×10⁸ and 5×10⁸ cfu/g B. subtilis had higher hepato-pancreas protease activities than those of fish fed the basal diet and a diet with 2×10⁶ cfu/g of B. subtilis. While the hepato-pancreas amylase activity, hepato-pancreas and intestine lipase activity were not affected significantly by dietary adding of B. subtilis (P>0.05), the body composition was not affected either. In conclusion, under the condition of this experiment, adding 2×10⁶—5×10⁸ cfu/g B. subtilis to fingerling black carp diet could improve fish growth and feed conversion without affecting the body composition.