Effects of dietary supplementation with distiller grain fermented liquid on growth performance, digestive and antioxidant capacity, and intestinal microbiota in juvenile Chinese mitten crab (Eriocheir sinensis)

Distiller grain fermented liquid (DGFL) is a novel feed additive for aquaculture. In this study, we investigated the effects of DGFL supplementation on the growth and physiology of juvenile Chinese mitten crabs Eriocheir sinensis . Crabs were randomly divided into two groups and fed either a basal diet (C group) or a diet supplemented with 5 % DGFL (T group) for 140d. Their growth performance, digestive and antioxidant capacities, and intestinal microbiota were measured. The final average weight, weight gain rate, specific growth rate, and hepatosomatic index of the T group were higher than those of the C group ( P < 0.05). Crude protein and total amino acid contents in the T group increased ( P < 0.05). The expression levels of digestive enzyme-related genes ( CTRB1 , TRYP , IL , and AMY ) and activities of α-amylase, lipase, trypsin, and pepsin were elevated in the T group ( P < 0.05). Total antioxidant capacity and superoxide dismutase and catalase activities in the hepatopancreas were enhanced in the T group ( P < 0.05), whereas malondialdehyde content decreased ( P < 0.05). The expression of antioxidant-related genes ( SOD , CAT , GPx , and Keap1 ) increased ( P < 0.05). Furthermore, 5 % DGFL improved hepatopancreatic and intestinal structural integrity, increased the α-diversity of the intestinal microbiota ( P < 0.05), elevated the abundance of Lactobacillales and Lactovum ( P < 0.05), and reduced the abundance of the conditional pathogen Vibrio . In conclusion, dietary 5 % DGFL enhanced growth performance, digestive and antioxidant capacities, intestinal structure, and microbiota composition of juvenile E. sinensis . This study, the first to investigate DGFL supplementation in this species, provides a strong theoretical basis for its use in aquafeeds. • 5 % DGFL increases weight gain and specific growth rates of juvenile E. sinensis . • 5 % DGFL improves hepatopancreas index of juvenile E. sinensis . • 5 % DGFL improves antioxidant and digestive abilities of juvenile E. sinensis . • 5 % DGFL increases Lactobacillales and Lactovum but reduces Vibrio abundance.