Effect of plant polysaccharides ( Poria cocos and Astragalus polysaccharides) on immune responses and intestinal microbiota of Dabry's sturgeons.

Searching for non-toxic and harmless feed ingredients that can improve growth performance and host immunity has always been the focus of attention in the protected areas for artificially bred Dabry's sturgeons. The present study explored the effect of dietary and polysaccharides on the antioxidant status, expression of immune related genes, and composition and putative functions of gut bacterial communities in Dabry's sturgeons for the first time. In this study, Dabry's sturgeons were randomly divided into 3 groups and fed diets of normal, polysaccharideadded (200 mg/kg), and polysaccharide-added (200 mg/kg) food for 14 days. The results indicated that dietary polysaccharide can increase the final body weight of Dabry's sturgeon. Compared with normal breeding individuals, feeding diets containing the and polysaccharides up-regulated the activity of superoxide dismutase, lysozyme, catalase, and glutathione peroxidase while also decreasing the levels of malondialdehyde. In addition, the polysaccharide group had higher gene expression of two inflammatory cytokines, tumor necrosis factor alpha and immunoglobulin M, than the control group. Analysis of intestinal microbiota revealed that the dietary polysaccharide improved the richness and diversity of major gut microbiota in Dabry's sturgeons, while the structure in the polysaccharide group was clearly distinguished from that of the control group. Our results preliminarily indicated that dietary supplementation of and polysaccharides may contribute to better performance in growth, development, and inflammatory response for Dabry's sturgeons, and they provide basic guidance for plant polysaccharide additives in artificial breeding of sturgeons.