To evaluate the effects of dietary pectin on growth performance, intestinal barrier, and antioxidant status of juvenile rainbow trout (), 10-week feeding trial was conducted. Five isoproteic and isoenergetic diets were formulated to contain 0% (P0), 4% (P4), 8% (P8), and 16% (P16) pectin as well as 0.02% pectinase (PE) at the expense of wheat starch, respectively. Dietary inclusion of 416% pectin linearly promoted the feed intake and growth performance but depressed the feed efficiency, but significant differences were only observed between the P16 and P0 groups. Similarly, dietary inclusion of 816% pectin significantly increased the foregut trypsin and amylase activities but decreased the foregut and midgut sucrase activity. The midgut gene expression level was significantly down-regulated by the inclusion of 16% pectin. Dietary inclusion of 2% pectin increased the abundance of Proteobacteria and but reduced the abundance of Actinobacteria, and ; while the lowest values of observed species, Chao1 and ACE indices of intestinal flora were found in the P8 group. Fish fed with the P8 diet exhibited the lowest plasma catalase and midgut glutathione S-transferase activities as well as malondialdehyde content, but the highest midgut malondialdehyde content. Dietary inclusion of 816% pectin significantly depressed the plasma growth hormone (GH), insulin-like growth factor-1 (IGF-1) and mechanistic target of rapamycin contents as well as alanine aminotransferase activity, the hepatic adenosine monophosphate deaminase and glutamate dehydrogenase (GDH) activities. Dietary treatment with 0.02% pectinase did not affect the growth performance, but depressed the foregut sucrase activity, the midgut amylase and sucrase activities, increased the plasma GH and IGF-1 contents as well as hepatic GDH and aspartate aminotransferase activities. In conclusion, high-dose of dietary pectin (816%) may promote the feed intake and intestinal digestive enzyme activities and thereby improve the growth performance of rainbow trout.

中文翻译：

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日粮果胶对虹鳟幼鱼（Oncorhynchus mykiss）生长性能、肠道屏障和抗氧化状态的影响

为了评估日粮果胶对虹鳟幼鱼生长性能、肠道屏障和抗氧化状态的影响，进行了 10 周的喂养试验。配制五种等蛋白和等能量日粮，其中含有 0% (P0)、4% (P4)、8% (P8) 和 16% (P16) 果胶以及 0.02% 果胶酶 (PE)，但以小麦淀粉为代价，分别。日粮中添加 416% 果胶可线性促进采食量和生长性能，但降低饲料效率，但仅在 P16 和 P0 组之间观察到显着差异。同样，饮食中添加 816% 果胶显着增加了前肠胰蛋白酶和淀粉酶活性，但降低了前肠和中肠蔗糖酶活性。 16%果胶的加入显着下调了中肠基因表达水平。膳食中添加 2% 果胶增加了变形菌门的丰度，但降低了放线菌门的丰度，并且；而观察到的物种、肠道菌群Chao1和ACE指数最低的是P8组。用P8饲料喂养的鱼表现出最低的血浆过氧化氢酶和中肠谷胱甘肽S-转移酶活性以及丙二醛含量，但中肠丙二醛含量最高。膳食中添加 816% 果胶可显着降低血浆生长激素 (GH)、胰岛素样生长因子-1 (IGF-1) 和雷帕霉素含量的机械靶标，以及丙氨酸转氨酶活性、肝单磷酸腺苷脱氨酶和谷氨酸脱氢酶（ GDH）活动。日粮中添加0.02%果胶酶不影响生长性能，但降低了前肠蔗糖酶、中肠淀粉酶和蔗糖酶活性，升高了血浆GH和IGF-1含量以及肝脏GDH和天冬氨酸转氨酶活性。综上所述，日粮中添加高剂量果胶（816%）可能会促进虹鳟鱼的采食量和肠道消化酶活性，从而提高其生长性能。