Bile Acid Supplementation with Degossypolized Cottonseed Oil Improves the Growth Performance, Digestive Enzyme Activity and Reduces Liver Inflammation in Larimichthys crocea Juvenile

Despite the numerous benefits associated with degossypolized cottonseed oil (DCSO), complete substitution of fish oil (FO) with DCSO in aquafeeds has been demonstrated to have deleterious effects on fish growth and health. The aim of the present study was to evaluate the impact of incorporating bile acid (BA) into the diets of juvenile large yellow croaker (Larimichthys crocea) with DCSO substitution. The experiment was conducted for ten weeks with a negative control group (FO, 100% fish oil), a positive control group (DCSO100, 100% DCSO), and two treatment groups, BA600 (600 mg/kg BA+DCSO100) and BA1200 (1200 mg/kg BA+DCSO100). The initial body weights of these fish were 7.55 g±0.40 g. The results demonstrated that incorporating BA into DCSO100 feed could substantially enhance fish growth and feed efficiency. Furthermore, BA inclusion influenced tissue fatty acid composition by reducing saturated fatty acids (SFAs) and increasing polyunsaturated fatty acids (PUFAs), particularly n-3 fatty acids, in both liver and muscle tissues. The BA600 diet enhanced the activity of α-amylase, lipase, and trypsin in the intestine, suggesting improved nutrient digestibility. Additionally, BA600 modulated hepatic lipid metabolism, as evidenced by decreased triglyceride (TG), total cholesterol (TC), and alanine aminotransferase (ALT) levels, as well as upregulated expressions of sterol regulatory element-binding protein 1 (srebp-1), fatty acid synthase (fas), and acyl-CoA oxidase (aco). BA600 also exhibited immunomodulatory effects, downregulating interleukin 6 (il-6), interleukin 1 Beta (il-1β), interferon Gamma (ifnγ), while upregulating interleukin 10 (il-10) and arginase 1 (arg-1). These findings demonstrate that dietary BA supplementation at 600 mg/kg effectively reduce the adverse effects of complete FO substitution with DCSO, thus represents a promising functional additive for optimizing DCSO-based aquafeeds in juvenile L. crocea aquaculture.