Bile acids supplementation promotes the growth of Procambarus clarkii and improves its ability to resist pathogens infection

• Dietary bile acids enhance growth and lipid metabolism in P. clarkii . • BAs reduce WSSV replication and enhance antiviral effector expression. • BAs modulate intestinal microbiota composition and function to promote intestinal homeostasis. Key challenges in aquaculture systems include low feed efficiency, frequent stress, and high disease incidence. Therefore, identifying feed additives that can promote growth and enhance stress resistance in aquatic animals represents a promising strategy. In this study, crayfish ( Procambarus clarkii ) fed a diet supplemented with bile acids (BAs) showed increased body weight, higher hepatopancreas index, and elevated triglyceride (TG) levels compared to the control group. Concurrently, lipid metabolism was enhanced, as evidenced by the upregulated expression of genes involved in lipogenesis, absorption, and β-oxidation. Moreover, dietary BAs significantly improved intestinal resistance to oxidative stress. BAs mediated the expression of ALF1 and proPO , thereby strengthening crayfish resistance to infections of both the White Spot Syndrome Virus (WSSV) and Vibrio parahaemolyticus ( Vp ). Furthermore, BAs markedly shaped the intestinal microbiota of crayfish, increasing the abundance of bacteria that promote carbohydrate and lipid metabolism while reducing the abundance of bacteria that disrupt intestinal microbial homeostasis. Predictive functional analysis indicated reduced bacterial motility and lipopolysaccharide (LPS) synthesis capacity. Collectively, these findings indicate that BAs represent a potential dietary additive for enhancing growth performance and disease resistance in crustaceans, a strategy that holds significant promise for sustainable aquaculture practices.