Xylooligosaccharides alleviate the carbohydrate-enriched diet-induced intestinal barrier dysfunction in carp Megalobrama amblycephala by promoting intestinal development, immunity and gut microbiota.

To date, although the high-carbohydrate (HC) feed has been extensively adopted in the aquaculture industry, its effects on the intestinal function and development of aquatic animals still remain unclear. In addition, the corresponding nutritional intervention is still barely reported. This study aimed to evaluate the influence of xylooligosaccharides (XOS) on the intestinal health of Megalobrama amblycephala subjected to a HC feeding. Fish (average weight: 44.55 ± 0.15 g) were randomly offered 3 diets, including a control one (29 % carbohydrate), a HC one (41 % carbohydrate), and a XOS supplemented one (HC + 1.0 % XOS, HCX) respectively for 12 weeks. The HC feeding caused morphological abnormalities of intestine, an increased intestinal permeability, and the intestinal immunosuppression, all of which were markedly reversed by XOS administration. In addition, compared with the HC group, HCX feeding remarkably promoted the intestinal activities of digestive and brush border enzymes, and the expressions of cell proliferation-related proteins (Wnt10b and Cyclin D1). The 16s rDNA sequencing also revealed that XOS administration increased the abundance of beneficial bacteria, and decreased that of pathogenic ones. In conclusion, dietary supplementation of XOS improved the intestinal histomorphology, barrier function, cell proliferation and bacterial communities of carbohydrate-overloaded fish Megalobrama amblycephala.