Effects of Different Monomeric Bile Acids in the Diet on the Growth and Lipid Metabolism of Juvenile Pacific White Shrimp

Bile acids are important for lipid digestion and metabolic regulation, but the roles of individual bile acids in crustaceans remain unclear. This study evaluated the effects of six dietary monomeric bile acids on growth and lipid metabolism in juvenile Pacific white shrimp. Juvenile shrimp (2.5 g) were fed a basal diet or the same diet supplemented with 0.04% bile acid (cholic acid, hyodeoxycholic acid, chenodeoxycholic acid, deoxycholic acid, ursodeoxycholic acid, or hyocholic acid) for 8 weeks. Each treatment was assigned to three replicate 100-L tanks, with 30 shrimp per tank. Dietary monomeric bile acids did not significantly affect growth performance, body composition, or muscle fatty acid composition. Compared with the control group, chenodeoxycholic acid, deoxycholic acid, and hyocholic acid significantly reduced the hemolymph triglyceride levels, while cholic acid, chenodeoxycholic acid, and hyocholic acid lowered the hepatopancreatic lipid levels. All bile acid treatments reduced the hepatopancreatic malondialdehyde content compared with the control group. Expression of genes related to bile acid transport, sterol metabolism, and lipid catabolism was generally upregulated by bile acids, indicating enhanced bile acid circulation and lipid turnover. In conclusion, monomeric bile acids mainly regulate lipid metabolism and oxidative status rather than directly promoting growth under the present dietary condition, with chenodeoxycholic acid, cholic acid, and deoxycholic acid showing relatively stronger effects.