Dietary n‐3 long chain polyunsaturated fatty acids affect the serum biochemical parameters, lipid‐metabolism‐related of gene expression and intestinal health of juvenile hybrid grouper (♀ <i>Epinephelus fuscoguttatus</i> × ♂ <i>Epinephelus lanceolatu</i> )
Wenqiang An, Xiaohui Dong, Beiping Tan, Qihui Yang, Shuyan Chi, Shuang Zhang, Hongyu Liu, Yuanzhi Yang
Abstract
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.