蝇蛆蛋白混合物对美洲鳗鲡非特异性免疫功能的影响

Effects of Maggot Protein Mixture on Non-Specific Immune Function of American Eel Anguilla rostrata

蝇蛆既是优质饲料蛋白质又是新型免疫增强剂。为探明蝇蛆蛋白混合物对美洲鳗鲡非特异性免疫功能的影响,水温为25~28℃时,将750尾初始体质量(95.0±5.0)g的美洲鳗鲡随机分为5组,每组3个平行,每个平行50尾鱼,分别投喂在基础饲料中添加质量分数为0%(对照组)、5%、10%、15%和20%蝇蛆蛋白(由蝇蛆蛋白混合物折算而来)的饲料,投喂养殖60 d后,测定美洲鳗鲡血清中溶菌酶、补体3、补体4、酸性磷酸酶、碱性磷酸酶、超氧化物歧化酶、谷丙转氨酶和谷草转氨酶等免疫指标的变动情况及嗜水气单胞菌攻毒后美洲鳗鲡的死亡率。试验结果显示:美洲鳗鲡血清中补体3、补体4含量随蝇蛆蛋白混合物添加比例增加而显著提高(P<0.05),其中补体3以15%添加组含量最高,补体4以20%添加组含量最高;血清中溶菌酶、酸性磷酸酶、碱性磷酸酶和超氧化物歧化酶活性均随蝇蛆蛋白混合物添加量的增加先升后降,除5%添加组碱性磷酸酶活性与对照组差异不显著外,其余均显著高于对照组(P<0.05),其中溶菌酶、酸性磷酸酶和超氧化物歧化酶均以15%添加组活性最高,碱性磷酸酶以10%添加组最高;谷丙转氨酶活性也随蝇蛆蛋白混合物添加量的增加先升后降,但蝇蛆蛋白添加量低于20%的处理组与对照组差异不显著(P>0.05);谷草转氨酶活性则随蝇蛆蛋白混合物添加量的增加逐渐下降,但只有蝇蛆蛋白添加水平超过15%后才显著低于对照组(P<0.05)。攻毒试验结果表明,15%添加组的美洲鳗鲡累积死亡率最低,与对照组差异显著,相对免疫保护率最高。综上所述,在饲料中添加蝇蛆蛋白混合物能显著提高美洲鳗鲡非特异性免疫功能和抗病力,最佳添加量为15%蝇蛆蛋白。

Maggot is not only a high quality feed protein,but also a new immune enhancer.To evaluate the effect of maggot protein mixture on the non-specific immunity of American eel Anguilla rostrata,seven hundred and fifty American eels with average initial body weight of(95.0±5.0)g were randomly divided into five groups with three replicates per group and 50 fish per replicate,were reared at water temperature of 25—28℃and fed basal diet supplemented with 0(control group),5%,10%,15%and 20%(converted from housefly maggot protein mixture)of maggot protein,respectively.After 60 d rearing,the activities of lysozyme,acid phosphatase,alkaline phosphatase,superoxide dismutase,glutamic-pyruvic transaminase and glutamic-oxaloaletic transaminase and contents of complement 3 and 4 were measured in serum of American eel,and the mortality also tested after American eels were infected with Aeromonas hydrophila.The results showed that the contents of complements 3 and 4 in serum were significantly increased with the increase maggot protein mixture in diets(P<0.05).The highest levels of contents for complements 3 and 4 were found in the 15%and 20%maggot protein added groups,respectively.The activities of the serum lysozyme,acid phosphatase,alkaline phosphatase and superoxide dismutase were increased first and then decreased with increasing maggot protein mixture supplementation,and significantly higher than those in the control group except the activity of alkaline phosphatase for the 5%maggot protein added group(P<0.05).The highest activities of lysozyme,acid phosphatase and superoxide dismutase were all exhibited in the 15%maggot protein added group.The activity of alkaline phosphatase reached the highest level in fish fed diet containing 10%maggot protein.Although the activity of the serum glutamic-pyruvic transaminase increased initially and then decreased with increasing maggot protein mixture supplementation,no significant difference was observed when supplementing maggot protein ratio was lower 20%(P>0.05).The activity of the serum glutamic-oxaloaletic transaminase was gradually decreased with the increase in supplementing maggot protein mixture,significant decrease compared to the control group when supplementing maggot protein mixture ratio was higher 15%(P<0.05).The challenge test revealed that there was significantly lower accumulated mortality and higher relative immune protective rate for American eel in the 15%maggot protein added group than that in control group.The findings indicated that dietary supplementation of maggot protein mixture elevated the non-specific immunity and disease resistance of American eel.It is suggested that supplementation with 15%maggot protein in diet is optimal for American eel.