To determine the effects of dietary n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) on lipid metabolism and intestinal health of juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu), an 8-week feeding experiment was carried out using six isoproteic and isolipidic formula diets containing 0.65% (control), 1.00%, 1.35%, 1.70%, 2.05% and 2.40% n-3 LC-PUFA (dry matter). The results showed that the serum triglyceride and cholesterol reached the minimum in the 1.70% group and 1.35% group, respectively. The serum glucose content of the control group was significantly lower than that of the other groups (p < 0.05). Compared with the control group, the expression of hepatic cpt-1 gene in the 2.05% group and atgl, apob-100 genes in the 2.40% group reached the maximum and increased significantly, while fas, accα and pparγ genes in the 2.05% and 2.40% groups decreased significantly (p < 0.05). The cpt-1, atgl and pparα gene expression in the muscle increased first and then decreased, reaching the maximum in the 1.70% and 1.35% groups, while the expression of fas and pparγ significantly decreased (p < 0.05), reaching the minimum in the 2.40% and 2.05% groups, respectively. Intestinal lipase and trypsin activities in the 2.05% group reached the maximum. In the intestine microbiota, Proteobacteria, Bacteroidetes and Firmicutes were the dominant phyla. The contents of Bacteroidales_S24-7_group and Lachnospiraceae increased with the addition n-3 LC-PUFA. In summary, the moderate dietary n-3 LC-PUFA (1.35%–1.70%) could up-regulate lipid catabolism gene expression and down-regulate lipid anabolism gene expression; dietary n-3 LC-PUFA significantly affected the structural integrity of the proximal intestine and improved the abundance of intestinal probiotics in hybrid grouper.

中文翻译：

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日粮n-3长链多不饱和脂肪酸对杂种石斑鱼(♀Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu)血清生化参数、基因表达的脂质代谢相关及肠道健康的影响

为了确定日粮n-3长链多不饱和脂肪酸（n-3 LC-PUFA）对杂种石斑鱼（♀Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu）脂质代谢和肠道健康的影响，进行了8周的饲养实验使用含有 0.65%（对照）、1.00%、1.35%、1.70%、2.05% 和 2.40% n-3 LC-PUFA（干物质）的六种等蛋白和等脂配方日粮。结果显示，血清甘油三酯和胆固醇分别在1.70%组和1.35%组达到最低。对照组血清葡萄糖含量显着低于其他组（p  < 0.05）。与对照组相比，肝脏cpt - 1的表达2.05%组和atgl、apob - 100基因在2.40%组达到最大值并显着增加，而fas、accα和pparγ基因在2.05%和2.40%组显着减少（p  <0.05）。的CPT - 1，ATGL和PPARα基因表达在肌肉先增加后降低，在1.70％和1.35％组达到最大，而表达FAS和PPARγ显著降低（p < 0.05)，分别达到 2.40% 和 2.05% 组的最小值。2.05%组肠道脂肪酶和胰蛋白酶活性达到最大值。在肠道微生物群中，变形菌门、拟杆菌门和厚壁菌门是优势门。Bacteroidales_S24-7_group 和 Lachnospiraceae 的含量随着 n-3 LC-PUFA 的加入而增加。综上所述，适度膳食n-3 LC-PUFA（1.35%~1.70%）可上调脂质分解代谢基因表达，下调脂质合成代谢基因表达；日粮 n-3 LC-PUFA 显着影响了近端肠道的结构完整性，并提高了杂种石斑鱼肠道益生菌的丰度。