Abstract This study explored the alleviation of salinity-induced stress by adding dietary prebiotic inulin in Nile tilapia Oreochromis niloticus. Tilapias were administrated with four levels of inulin (0, 0.2%, 0.4% and 0.8%) at the salinity of 16 psu (practical salinity unit) for 8 weeks, and meanwhile the tilapia fed the basal diet in freshwater were served as a freshwater control. The final weight, weight gain, and specific growth rate increased but feed conversion ratio decreased in the 16 psu group compared to the freshwater group. These trends became more evident in groups of 16 psu + 0.2% inulin and 16 psu + 0.4% inulin, and the best growth was obtained in the 16 psu + 0.4% inulin group. SOD activity was significantly elevated while CAT and GST activities were markedly reduced in 16 psu group compared to the freshwater group, but these parameters returned to the freshwater group level when tilapia were fed with 0.4% inulin. Amylase and protease activities were significantly increased in 16 psu group compared to the freshwater group, but reduced and returned to the level of freshwater group by adding 0.2% and 0.4% inulin to the diet. The composition, α-diversity, and β-diversity of gut microbiota were disturbed in 16 psu group, but returned to the freshwater group pattern in 16 psu + 0.8% inulin group. The results show that dietary inulin is an effective feed additive to alleviate the oxidative stress and gut microbiota dysbiosis at 16 psu. This study suggests that dietary manipulation using inulin is a promising strategy to improve fish healthy under saline stress, and the optimal level of inulin supplementation to the diet is 0.4% for Nile tilapia at 16 psu.

中文翻译：

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菊粉减轻高盐度应激引起的氧化应激和尼罗罗非鱼（Oreochromis niloticus）肠道微生物群的失调

摘要 本研究探讨了通过在尼罗罗非鱼 Oreochromis niloticus 中添加日粮益生元菊粉来缓解盐分胁迫。在16 psu（实用盐度单位）的盐度下给罗非鱼施用四种水平的菊粉（0、0.2%、0.4%和0.8%）8周，同时在淡水中饲喂基础饲料的罗非鱼作为淡水控制。与淡水组相比，16 psu 组的最终体重、增重和比生长率增加，但饲料转化率降低。这些趋势在 16 psu + 0.2% 菊粉和 16 psu + 0.4% 菊粉组中变得更加明显，并且在 16 psu + 0.4% 菊粉组中获得最佳生长。与淡水组相比，16 psu 组的 SOD 活性显着升高，而 CAT 和 GST 活性显着降低，但当罗非鱼喂食 0.4% 菊粉时，这些参数恢复到淡水组水平。与淡水组相比，16 psu 组的淀粉酶和蛋白酶活性显着增加，但在日粮中添加 0.2% 和 0.4% 菊粉后降低并恢复到淡水组的水平。肠道菌群的组成、α-多样性和β-多样性在 16 psu 组中受到干扰，但在 16 psu + 0.8% 菊粉组中恢复到淡水组模式。结果表明，日粮菊粉是一种有效的饲料添加剂，可在 16 psu 时缓解氧化应激和肠道微生物群失调。这项研究表明，使用菊粉进行日粮操作是改善盐胁迫下鱼类健康的一种有前景的策略，对于 16 psu 的尼罗罗非鱼，日粮中菊粉的最佳补充水平为 0.4%。