Effectiveness of bile acids as a feed supplement to improve growth performance, feed utilization, lipid metabolism, digestive enzymes, and hepatic antioxidant status in aquaculture animals: A meta-analysis

Abstract

The present systematic review and meta-analysis was performed to quantitatively assess the efficacy of dietary supplementation of bile acids on growth performance, feed utilization and physiological parameters in aquaculture species. Hedges’ g effect size and corresponding 95% confidence intervals were calculated to quantify differences in outcome indicators in an experimental dietary treatment group relative to a control group. The publication bias analysis was evaluated to the robustness of the pooled estimates. Potential sources of heterogeneity were explored using sensitivity test, subgroup analysis, and meta-regression analysis. All analyses were performed using metafor and ggplot2 packages in the program R. Overall, the meta-results indicated that dietary bile acids supplementation caused a significant increase in final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), protein efficiency ratio (PER), circulating high-density lipoprotein cholesterol (HDL-C), digestive enzymes (lipase, protease, amylase), hepatic superoxide dismutase (SOD) activity, serum or plasma lysozyme, alkaline phosphatase (ALP), immunoglobulins, as well as a significant decrease in feed conversion ratio (FCR), circulating triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), hepatic lipid content (HLC), and hepatic malondialdehyde (MDA) content. A moderate or large heterogeneity was identified across the studies for the outcome parameters except hepatic lipid content (HLC). Furthermore, the meta-regression analysis showed that the optimum levels of bile acids as a feed additive were estimated to be 60-188.42, 989.42, 437.43-989.42, 3751.28-3946.59mg/kg diet for low trophic-level freshwater fish, medium trophic-level freshwater fish, medium trophic-level marine fish, and high trophic-level marine fish, respectively. Therefore, bile acids is a promising growth-promoting and lipid-lowering feed supplement for sustainable aquaculture industry.