大蒜素对大菱鲆幼鱼生长及抗病力的影响

Effects of Allicin on Growth and Disease Resistance in Turbot

在水温13~15℃、盐度30条件下,将体质量(8.12±0.03)g的大菱鲆幼鱼饲养在5.0 m×5.0 m×0.6 m的水泥池中,每池3600尾,投喂每千克饲料中分别拌入0(对照)、100、200、400、800 mg大蒜素的饲料,饲养6周。养殖试验结束时,腹腔注射鳗弧菌,连续14 d感染攻毒;饥饿24 h后,全池称量质量,尾静脉采血,测定血清中补体C3含量和溶菌酶、超氧化物歧化酶活性,研究大蒜素对大菱鲆幼鱼生长、非特异性免疫力及抗病力的影响。试验结果显示,大菱鲆幼鱼的特定生长率随着饲料中大蒜素含量的增加而逐渐升高,并在大蒜素添加量为200 mg/kg及以上时显著高于对照组(P<0.05);对照组存活率显著低于其他各组(P<0.05)。饲料系数随饲料中大蒜素含量的增加而逐渐降低,并在100 mg/kg及以上时显著低于对照组(P<0.05),但在200 mg/kg及以上时保持稳定。血清补体C3含量随饲料中大蒜素含量的增加呈先升后降的趋势,在200、400 mg/kg组达最大值并显著高于其他各组(P<0.05)。溶菌酶活力、超氧化物歧化酶活力则随大蒜素含量的增加而逐渐升高,并在大蒜素含量达400 mg/kg及以上时不再有显著变化。人工感染试验表明,400、800 mg/kg组的感染死亡率显著低于其他各组(P<0.05)。综上,饲料中添加200 mg/kg的大蒜素有利于大菱鲆幼鱼生长,而400 mg/kg的大蒜素能更有效地提高其非特异性免疫力及抗病力。

Juvenile turbot(Scophthalmus maximus)with body weight of(8.12±0.03)g was reared in cement ponds of each 5.0 m×5.0 m×0.6 m at stocking density of 3600 individuals per pond and fed diets containing 0(control),100,200,400,and 800 mg/kg diet allicin at water temperature of 13—15℃and a salinity of 30 for 6 weeks.At the end of the feeding trial,pathogen Vibrio anguillarum was injected intraperitoneally into the turbot for 14 days to infect;after 24 hours of starvation,the sample fish was weighed and blood was collected from caudal peduncle vein to determine the content of complement C3,and the activities of lysozyme and superoxide dismutase(SOD)in serum to explore the effects of allicin on the growth,non-specific immunity and disease resistance of turbot.It was found that the specific growth rate was increased with the increasing level of dietary allicin,significantly higher in the juveniles fed diets containing allicin up to 200 mg/kg and over than that in the juveniles in control group(P<0.05).The fish fed control diet had significantly lower survival rate than the fish in other groups did(P<0.05).The food conversion ratio was shown to be decreased with the increase in dietary allicin,significantly lower than that in the 100 mg/kg group,and stable in the dietary allicin up to 200 mg/kg group.Serum complement C3 contents were increased with the increasing level of dietary allicin from 0 to 400 mg/kg,with the maximal C3 contents in 200 and 400 mg/kg groups,significantly higher than any other groups(P<0.05).The lysozyme and SOD activities in serum were found to be increased with the increasing level of dietary allicin,without significant increase in dietary allicin up to 400 mg/kg group.The challenge test indicated that the infection mortalities in treatment of 400 and 800 mg allicin/kg diet were significantly lower than that in any other treatments(P<0.05).Therefore,it is recommended that 200 mg/kg diet be essential to maintain the optimal growth for the juvenile turbot,and 400 mg/kg diet leads to improve nonspecific immunity and ability to fight enteritis more effectively.