The effects of astaxanthin supplementationon the growth, innate immunity and antioxidant defence system of loach (Paramisgurnus dabryanus) were investigated in this study. A total of 450 fish (initial average weights of 3.00 ± 0.10 g) were fed five diets with graded levels of astaxanthin (0.00, 50.00, 100.00, 150.00 and 200.00 mg/kg) for 56 days. The results showed that astaxanthin supplementation significantly stimulated the growth (FBW, WG, FER, HSI), innate immunity (AKP activity in the hepatopancreas, intestinal tract, muscle and skin and LZM activity in the hepatopancreas, intestinal tract and skin), antioxidant ability (T‐SOD, GSH‐PX and CAT activities and T‐AOC, GSH and MDA contents in the hepatopancreas, intestinal tract, muscle and skin) of loach. Moreover, dietary astaxanthin supplementation significantly up‐regulated the relative mRNA levels of Nrf2 and Maf, and down‐regulated the relative mRNA level of Keap1 in the hepatopancreas when the supplementation levels of astaxanthin were 50–200 mg/kg. In conclusion, the diets with 100–151.06 mg/kg astaxanthin supplementation were optimal for loach, which based on the growth, immunity and antioxidant‐related indicators, and the astaxanthin supplementation regulated the antioxidant ability partially referring to Keap1‐Nrf2 signallings.

中文翻译：

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日粮虾青素对大白菜生长，先天免疫和抗氧化防御系统的影响

虾青素的影响supplementationon增长，先天免疫和泥鳅的抗氧化防御系统（大鳞副泥鳅）进行了这项研究。总共对450条鱼（初始平均重量为3.00±0.10克）喂食了五种日粮虾青素含量分别为0.00、50.00、100.00、150.00和200.00 mg / kg的日粮，持续56天。结果表明，补充虾青素可显着刺激生长（FBW，WG，FER，HSI），先天免疫（肝胰腺，肠道，肌肉和皮肤中的AKP活性以及肝胰腺，肠道和皮肤中的LZM活性），抗氧化能力（泥ach中的T-SOD，GSH-PX和CAT活性以及肝胰腺，肠道，肌肉和皮肤中的T-AOC，GSH和MDA含量）。此外，日粮虾青素的添加显着上调了Nrf2和Maf的相对mRNA水平，而下调了Nrf2和Maf的相对mRNA水平。当虾青素的补充水平为50-200 mg / kg时，肝胰腺中的Keap1。总之，根据生长，免疫力和与抗氧化剂相关的指标，添加100–151.06 mg / kg虾青素的饮食最适合泥ach，而虾青素的添加部分通过Keap1-Nrf2信号传导来调节抗氧化能力。