饲料中添加新型金藻对虹鳟幼鱼肝脏抗氧化性能的影响

Effects of New Dietary Chrysophyte on Liver Antioxidant Performance in Juvenile Rainbow Trout

在水温(14±0.5)℃下,将体质量(10.40±0.13)g的虹鳟(Oncorhynchus mykiss)幼鱼饲养在流速0.4 m/s(总水体约8 m^(3))的圆柱形培育缸中,表观饱食投喂添加0%、2%、4%和8%富含β-葡聚糖的新型金藻饲料8周后,从每组随机采鱼50尾,麻醉后腹腔注射浓度为7.2×10^(8)CFU/m L的杀鲑气单胞菌(Aeromonas salmonicida)菌液0.1 m L,统计3 d与7 d致死率,并比较饲料中添加新型金藻(Poterioochromonas malhamensis)对虹鳟幼鱼攻毒前后肝脏抗氧化性能的影响。结果显示:2%、4%处理组攻毒后死亡率明显低于对照组;养殖实验结束后,2%、4%处理组虹鳟肝超氧化物歧化酶(SOD)活性显著高于对照组,2%处理组过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPx)活性显著高于对照组,4%、8%处理组虹鳟肝丙二醛(MDA)含量显著高于对照组(P<0.05);对照组、4%处理组与8%处理组虹鳟肝SOD活性均在攻毒3 d时达最大值,显著高于攻毒7 d时(P<0.05);对照组和8%处理组CAT活性均显著高于攻毒前(P<0.05);2%处理组GPx活性在攻毒后显著降低(P<0.05);8%处理组随着攻毒时间的延长MDA浓度显著升高(P<0.05)。结果表明,在饲料中添加适宜比例(2%~4%)的富含β-葡聚糖的新型金藻能降低虹鳟感染杀鲑气单胞菌后的死亡率,提高其攻毒前后肝脏的抗氧化性能。

Juvenile rainbow trout(Oncorhynchus mykiss)with body weight of(10.40±0.13)g were reared in a cylindrical cultivation tank with a flow rate of 0.4 m/s(total water volume of about 8 m^(3))and fed diets containing 0%(control group),2%,4%and 8%of the new chrysophyte rich inβ-glucan at water temperature of(14±0.5)℃for 8 weeks.Then 50 fish were randomly selected from each group,and challenged with 0.1 m L of Aeromonas salmonicida at concentration of 7.2×10^(8)CFU/m L,and the lethality rates were calculated in 3 d and 7 d to evaluate the effects of dietary chrysophyte on mortality and antioxidant performance of rainbow trout.The results showed that there was a decrease in mortality in rainbow trout challenged with A.salmonicida in 2%and 4%new chrysophyte groups compared with that in control group.At the end of feeding trial,significantly higher liver superoxide dismutase(SOD)activity was observed in 2%and 4%new chrysophyte groups compared with that in control group,with significantly higher liver catalase(CAT)and glutathione peroxidase(GPx)activities in 2%new chrysophyte group(P<0.05).Increases in MDA contents were also observed in rainbow trout in 4%and 8%new chrysophyte groups compared with that in control group(P<0.05).The peak liver SOD activity was found in rainbow trout challenged with A.salmonicida in control,4%and 8%new chrysophyte groups at day 3,significantly higher than that at day 7.Significantly higher liver CAT activity was observed in 8%new chrysophyte group at day 3 and day7 than that in day 0(P<0.05),with significant decrease in GPx in 2%new chrysophyte group after infection(P<0.05).There was significant increase in the content of MDA in 8%new chrysophyte group with the prolonged infection period(P<0.05).The findings indicate that diets containing optimal levels of this new chrysophyte are beneficial for enhancing resistance against A.salmonicida and affecting their antioxidant performance in rainbow trout.