饲料中添加溶菌酶对吉富罗非鱼生长、免疫-抗氧化功能及血清抗菌性能的影响

为研究在饲料中添加不同水平的溶菌酶制品对吉富罗非鱼(GIFT, Oreochromis niloticus)生长性能、免疫-抗氧化功能和血清抗菌性能的影响, 选用平均体重为(11.350.08)g的吉富罗非鱼960尾, 随机分为6组(每组4个重复, 每个重复40尾), 分别投喂基础饲料(对照组)和5种添加水平分别为18、36、54、72和90 mg/kg溶菌酶制品的试验饲料, 养殖周期为60d。结果表明: (1) 54 mg/kg溶菌酶添加组鱼的生长性能和饲料利用情况最优, 增重率和蛋白质效率均显著高于对照组, 饲料系数显著低于对照组(P0.05); 肝体比随溶菌酶添加水平的增加呈现下降趋势, 90 mg/kg添加组显著低于对照组(P0.05); 脾脏指数在36和54mg/kg添加组显著低于对照组(P0.05); 全鱼粗蛋白和粗灰分含量在54 mg/kg添加组均呈现较高水平, 显著高于对照组(P0.05)。(2)溶菌酶添加水平对罗非鱼的免疫-抗氧化能力产生影响, 54和72 mg/kg添加水平能显著提高鱼体血清和肝脏的超氧化物歧化酶、过氧化氢酶活性, 降低丙二醛含量(P0.05); 肝脏溶菌酶活性在54和72 mg/kg添加组均显著高于对照组(P0.05), 而血清溶菌酶活性随溶菌酶添加水平的增加呈现下降趋势(L90组除外), 显著低于对照组(P0.05)。(3)血清抗菌试验显示, 54和72 mg/kg溶菌酶添加组罗非鱼对大肠杆菌、金黄色葡萄球菌、嗜水气单胞菌和溶藻弧菌的抑制能力显著高于对照组(P0.05), 而对枯草芽孢杆菌的抵抗能力最低, 比对照组分别低34.71%和42.21% (P0.05)。结果表明, 在本试验条件下, 在吉富罗非鱼饲料中添加54 mg/kg溶菌酶制品可以改善其生长性能; 当添加水平为54和72 mg/kg时, 罗非鱼的免疫-抗氧化能力和血清抗菌性能均得到了显著提高。

EFFECTS OF DIETARY LYSOZYME SUPPLEMENTATION ON GROWTH PERFORMANCE,IMMUNE-ANTIOXIDANT CAPACITY AND SERUM ANTIBACTERIAL PROPERTIES OF GIFT TILAPIA (OREOCHROMIS NILOTICUS)

To investigate effects of dietary lysozyme supplementation on growth performance, immune-antioxidant ca-pacity and antibacterial properties of GIFT tilapia (Oreochromis niloticus), basal diet or basal diet added with 18, 36, 54, 72 or 90 mg/kg lysozyme were formulated for a 60 days experiment. The results showed that the 54 mg/kg lyso-zyme addition group had the best growth and feed efficiency in which weight gain rate and protein efficiency ratio in-creased and feed conversion ratio decreased significantly compared with the control group (P<0.05). Lysozyme supple-mentation decreased hepatosomatic index with significant difference in 90 mg/kg group compared with the control group (P<0.05). Spleen-somatic index was significantly lower in 36 mg/kg and 54 mg/kg groups compared with that of the control group (P<0.05). Crude protein and ash content in whole body in 54 mg/kg group were significantly higher than that of the control group (P<0.05). Lysozyme supplementation in 54 and 72 mg/kg group increased serum and li-ver superoxide dismutase and catalase activity but significantly decreased malondialdehyde content compared with the control group (P<0.05). Liver lysozyme activity in 54 and 72 mg/kg group was significantly higher than that of the con-trol group, while serum lysozyme activity in groups except L90 group was significantly lower than that of the control group (P<0.05). Serum antibacterial test showed more resistance to Escherichia coli, Staphylococcus aureus, Aeromo-nas hydrophila, Vibrio alginolyticus in 54 and 72 mg/kg group compared with the control group but more sensitive to Bacillus subtilis with a 34.71%and 42.21%reduction, respectively. These results indicated that diet lysozyme supple-mentation (such as 54 mg/kg) can improve GIFT tilapia growth performance by regulating immune-antioxidant capa-city of tilapia and improving serum antibacterial properties.