Effects of different dietary lipid levels on intestinal mucosal barrier and microbial community of juvenile tiger puffer Takifugu rubripes

A 65‐day feeding trial was conducted to investigate the effects of different levels of dietary lipid on intestinal health of tiger puffer. Three experimental diets were formulated, differing in lipid level, that is, 90.3 (control‐suitable lipid, C‐SL), 130.3 (moderately high lipid, MHL) and 170.3 (extremely high lipid, EHL) g/kg dry matter. The results showed that with increasing dietary lipid levels, the activities of total antioxidant capacity, Na+ K+‐ATP, amylase and trypsin were significantly decreased by diets MHL and EHL. Compared with C‐SL, the mRNA expression of the intestinal tight junction proteins (Claudin14, Claudin18, junctional adhesion molecule‐A) were significantly down‐regulated and the serum diamine oxidase enzyme activity was significantly increased in the EHL group. Diet EHL up‐regulated the gene expression of the pro‐inflammatory cytokines, tumour necrosis factor‐α, interferon‐2, interleukin (IL)‐1β, IL‐8 and IL‐15, and down‐regulated that of anti‐inflammatory cytokine transforming growth factor ‐β. Sequencing of intestinal bacterial 16s rRNA V4 region showed that diet EHL significantly increased the Firmicutes/Bacteroidetes ratio, decreased the alpha diversity of intestinal microbiota and the relative abundance of some potential beneficial bacteria such as Lactobacillus, Sphingomonas and Thermus. These results showed that high level of dietary lipid (170.3 g/kg) had negative effects on function status, mucosal barrier and microbial communities of tiger puffer intestine, indicating that tiger puffer was sensitive to the dietary lipid level.