Interaction between dietary lipid and bile acids on the growth performance and lipid metabolism in abalone Haliotis discus hannai Ino

A 105-day feeding trail was conducted to evaluate the effects of dietary lipid and bile acids levels as well as their interactions on the growth, digestion and lipid metabolism in abalone Haliotis discus hannai (initial weight: 5.29 +/- 0.02 g). Eight isonitrogenous diets with two levels of lipid (4.3% and 6.3%) and four levels of bile acids (0, 15, 60 and 240 mg/kg) were formulated in a 2 x 4 two-factor design. The results showed that 6.3% of dietary lipid decreased the weight gain rate (WGR) of abalone, which increased as the dietary bile acids level increasing from 0 mg/kg to 60 mg/kg. The treatment with the highest WGR contained 4.3% of dietary lipid and 60 mg/kg of dietary bile acids. In the groups with 4.3% of dietary lipid, the expression of genes involved in lipid transport and lipolysis was increased (P < 0.05). And dietary bile acids increased the expression of genes involved in lipid transport and lipolysis while decreased the expression of genes involved in lipogenesis (P < 0.05). The expression of genes involved in lipid metabolism, such as cluster of differentiation, fatty acid transport protein, microsomal triglyceride transfer protein and peroxisome proliferator-activated receptor alpha, revealed the interactions between dietary lipid and bile acids (P < 0.05). In conclusion, the growth and digestion of abalone were negatively impacted by an excessively high dietary lipid content (6.3%). Appropriate supplemented level of dietary bile acids (60 mg/kg) significantly enhanced the growth and digestion of abalone. Dietary lipid and bile acids had an interactive effect on the lipid metabolism in abalone, including lipid transport, lipolysis and lipogenesis.