Dietary bile acids supplementation improves the growth performance with regulation of serum biochemical parameters and intestinal microbiota of growth retarded European eels (Anguilla anguilla) cultured in cement tanks

The present trial was conducted to investigate the effects of bile acids on growth performance, digestive enzymes activities, serum biochemical parameters and intestinal microbiota on growth of retarded European eels (Anguilla anguilla) cultured in cement tanks. The trial fish with similar body size (about 140g per fish) cultured in nine cement tanks (fish weight, 681.7±22.7 kg per tank) were randomly divided into three groups and fed diets with bile acids supplementation at a level of 0, 500, and 1000 mg/kg, respectively. The trial period was 15 weeks. Dietary bile acids supplementation improved weight gain rate, feed intake, and activities of protease and lipase in intestine. There were also increases in levels of immunoglobulin and complements as well as activities of alkaline phosphatase (only in 1000 mg/kg bile acids group), acid phosphatase and lysozyme in serum. The levels of blood urea nitrogen, total cholesterol, triglyceride, low density lipoprotein cholesterol and activities of glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase were decreased by dietary bile acids supplementation. There were no significant differences in growth performance or serum biochemical parameters except the lysozyme activity between two bile acids supplementation groups. Dietary bile acids supplementation could increase richness and decrease diversity of the intestinal microbiota with different enriched bacteria at genus level. In conclusion, this study demonstrated that 500 mg/kg bile acids supplementation in the diet of growth retarded European eels cultured in cement tanks could promote growth performance, improve some digestive enzymes activities, and beneficially regulate serum biochemical parameters and intestinal microbiota.