To evaluate the effects of dietary nano‐selenium (Nano‐Se) on antioxidant capacity and hypoxia tolerance of grass carp fed with high‐fat diet, experimental fishes were fed Nano‐Se supplemented diets at doses of 0 (Control), 0.3, 0.6, 0.9 and 1.2 mg/kg for 10 weeks. After feeding trial, a part of the fishes were exposed to hypoxia stress. Results showed that the survival ratio of grass carp significantly increased in 0.6 and 0.9 mg/kg Nano‐Se group, and the content of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) significantly decreased in 0.6–1.2 mg/kg Nano‐Se groups compared with the control group. In addition, dietary Nano‐Se significantly enhanced glutathione peroxidase (GPX) activity and reduced the malondialdehyde (MDA) content in fishes fed diets with 0.3 and 0.6 mg/kg Nano‐Se. Dietary Nano‐Se significantly elevated mRNA expression of GPX1 and catalase (CAT) by promoting the mRNA expression of NF‐E2‐related nuclear factor 2 (Nrf2) in the hepatopancreas. After hypoxia stress, the GPX and superoxide dismutase (SOD) activities were significantly enhanced, and the MDA content and mortality rate consequently decreased in fishes fed diets with 0.3 and 0.6 mg/kg Nano‐Se. In summary, these results suggested that optimal Nano‐Se in diet enhanced the antioxidant capacity and hypoxia tolerance of grass carp.

中文翻译：

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膳食纳米硒增强高脂饲料饲喂草鱼的抗氧化能力和耐缺氧能力

为了评估日粮纳米硒（Nano-Se）对高脂饲料饲喂草鱼的抗氧化能力和缺氧耐受性的影响，实验鱼以 0（对照）、0.3、0.6 剂量的纳米硒饲料喂养, 0.9 和 1.2 mg/kg 持续 10 周。试饲后，部分鱼处于缺氧应激状态。结果表明，0.6、0.9 mg/kg Nano-Se组草鱼存活率显着提高，0.6-1.2 mg/kg Nano-Se组血清丙氨酸氨基转移酶（ALT）和天冬氨酸氨基转移酶（AST）含量显着降低。 Se组与对照组比较。此外，日粮纳米硒显着增强了谷胱甘肽过氧化物酶 (GPX) 活性，并降低了喂食 0.3 和 0.6 毫克/千克纳米硒日粮的鱼中的丙二醛 (MDA) 含量。膳食纳米硒通过促进肝胰腺中 NF-E2 相关核因子 2 (Nrf2) 的 mRNA 表达，显着提高 GPX1 和过氧化氢酶 (CAT) 的 mRNA 表达。缺氧胁迫后，GPX和超氧化物歧化酶（SOD）活性显着增强，喂食0.3和0.6 mg/kg纳米硒饲料的鱼的MDA含量和死亡率因此降低。总之，这些结果表明日粮中最佳的纳米硒增强了草鱼的抗氧化能力和耐缺氧能力。因此，饲喂 0.3 和 0.6 mg/kg Nano-Se 的鱼的 MDA 含量和死亡率降低。总之，这些结果表明日粮中最佳的纳米硒增强了草鱼的抗氧化能力和耐缺氧能力。因此，饲喂 0.3 和 0.6 mg/kg Nano-Se 的鱼的 MDA 含量和死亡率降低。总之，这些结果表明日粮中最佳的纳米硒增强了草鱼的抗氧化能力和耐缺氧能力。