Effect of dietary bile acid (BA) on the growth performance, body composition, antioxidant responses and expression of lipid metabolism-related genes of juvenile large yellow croaker (Larimichthys crocea) fed high-lipid diets

The present study was conducted to investigate the effects of dietary bile acid (BA) on the growth performance, body composition, antioxidant responses and expression of lipid metabolism-related genes of juvenile large yellow croaker (Larimichthys crocea) (average weight, 12.00 ± 0.20 g). An optimal lipid diet formulated with 4.0% fish oil and 4.0% soybean oil was set as the positive control diet (MO), while a high-lipid diet formulated with 6.5% fish oil and 6.5% soybean oil was used as the negative control diet (HO). The other three diets were supplemented with 150 (HOB150), 300 (HOB300) and 450 mg/kg (HOB450) BA on the basis of the negative control diet. The results showed that the survival rate (SR) was not significantly different among dietary treatments (P > 0. 05). Compared with the positive control, there were no significant differences in final body weight (FBW) and weight gain rate (WGR) among fish fed diets with high lipid contents. With increasing supplementation of BA in diets, the FBW and WGR gradually increased. Compared with the negative control, fish fed the diet with 300 mg/kg BA had significantly higher FBW and WGR (P < .05). The liver lipid content and liver malondialdehyde (MDA) content significantly decreased with increasing dietary BA (P < .05). In fish fed diets with 300 mg/kg-450 mg/kg BA, the activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were significantly increased (P < .05). The sterol regulatory element binding protein-1 (SREBP-1) mRNA expression levels in the liver significantly decreased with increasing dietary BA (P < .05). Furthermore, increasing dietary BA from 150 mg/kg to 450 mg/kg significantly improved the mRNA expression levels of peroxisome proliferator activated receptor α (PPARα), carnitine palmitoyltransferase 1 (CPT1) and acyl-CoA oxidase (ACO) in the liver (P < .05). These results suggested that dietary BA supplementation could improve the digestion and absorption capacity of lipids, which might be the reason for the improvement in the growth performance of large yellow croaker.