虾青素对饲料组胺胁迫下美洲鳗鲡(Anguilla rostrata)幼鱼生长性能、血清生化、肠道自由基水平及肠道菌群的影响

氧化应激是饲料组胺胁迫对鱼体产生危害的主要途径之一。研究具有强抗氧化能力的虾青素对美洲鳗鲡幼鱼饲料组胺胁迫的缓解效果, 对降低鱼类饲料源胁迫具有重要意义。将400尾初始体重为(25.01±0.17) g/尾的试验鱼随机分为4个处理组, 即对照组、H组、H+Ast4组和H+Ast8组, 分别饲喂基础饲料、高组胺饲料(662 mg/kg)及在高组胺饲料中添加4 mg/kg、8 mg/kg虾青素的试验饲料。结果显示: 与对照组相比, H组美洲鳗鲡幼鱼生长性能和血清非特异性免疫能力显著降低(P<0.05),肠道自由基水平显著升高(P<0.05),肠道有害菌群丰度升高; H+Ast组美洲鳗鲡幼鱼的生长性能、血清非特异性免疫能力显著高于H组(P<0.05),肠道自由基水平显著低于H组(P<0.05), 上述指标H+Ast组与对照组无显著差异(P>0.05)。H+Ast组肠道有益菌群丰度高于H组和对照组。可见, 添加4 mg/kg虾青素即可缓解饲料组胺胁迫导致的美洲鳗鲡幼鱼生长抑制, 提高血清非特异性免疫能力, 降低肠道自由基水平, 有益调节肠道菌群。添加8 mg/kg虾青素对美洲鳗鲡幼鱼上述指标无进一步的改善效果。研究结果可为虾青素缓解美洲鳗鲡饲料组胺胁迫及其在饲料中的推广应用提供参考。

EFFECTS OF ASTAXANTHIN ON GROWTH PERFORMANCE, SERUM BIOCHEMISTRY, INTESTINAL FREE RADICAL LEVEL AND INTESTINAL FLORA OF JUVENILE AMERICAN EEL (ANGUILLA ROSTRATA) UNDER DIETARY HISTAMINE STRESS

Oxidative stress is one of the major ways in which dietary histamine stress could cause detrimental effects on fish. It is important to study the alleviation effects of dietary astaxanthin with strong antioxidant capacity on the dietary histamine stress in juvenile American eels (Anguilla rostrata). Four hundred trial fish in initial body weight of (25.01±0.17) g/fish were randomly divided into four treatment groups. They were the control group fed a basal diet, the H group fed a diet with a high level of histamine (662 mg/kg), the H⁺Ast4 group fed the high histamine diet with 4 mg/kg astaxanthin, and the H+Ast8 group fed the high histamine diet with 8 mg/kg astaxanthin. Compared with the control group, the growth performance and non-specific immunity in the serum of juvenile A. rostrata in the H group were significantly decreased (P<0.05), the levels of intestinal free radicals in the H group were significantly increased (P<0.05), and the relative abundances of potentially pathogenic bacteria were increased. The growth performance and non-specific immunity in the serum of juvenile A. rostrata in the H⁺Ast groups were significantly higher than those in the H group (P<0.05), and the levels of intestinal free radicals were significantly lower than those in the H group (P<0.05), no significant difference in the aforesaid parameters was found between H⁺Ast groups and the control group (P>0.05). The relative abundances of the potential probiotics in the H⁺Ast groups were higher than those in the H group and control group. In conclusion, the addition of 4 mg/kg astaxanthin could alleviate the growth retardation of juvenile A. rostrata induced by dietary histamine stress, improve serum non-specific immunity, reduce the level of intestinal free radicals, and regulate intestinal microflora beneficially. Dietary 8 mg/kg astaxanthin might not exert further improvement in all parameters of juvenile A. rostrata in the present trial. These results provide certain references for astaxanthin alleviating dietary histamine stress and promote its application in the feed for A. rostrata.