EFFECTS OF DIETARY BILE ACID SUPPLEMENTATION ON THE GROWTH, WHOLE-BODY COMPOSITION AND APPARENT NUTRIENT DIGESTIBILITY OF BULLFROG (RANA CATESBEIANA)

To investigate the effects of dietary bile acids (BAs) on growth performance, body composition and apparent digestibility of dry matter, protein and lipid in diets for bullfrog, Rana catesbeiana, one hundred and forty-four bullfrogs were randomized to the same diet supplemented with four different levels of BAs (0, 100, 200, and 300 mg/kg). Compared with the control group, percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER) and nitrogen retention rate (NRR) of bullfrog were significantly higher at 200 mg/kg BAs-supplemented diet (P0.05), whereas feeding rate (FR) and survival rate (SR) had no significant differences cross groups (P0.05). BAs did not significantly affect the contents of moisture, crude protein, crude ash in muscle and body of bullfrog, but it significantly decreased body lipid content without interfering muscle lipid content. No significant differences were found on the levels of triglycerides (TG), cholesterol (CHO), high density lipoprotein cholesterol (HDL) and low density lipoprotein cholesterol (LDL) in serum cross groups (P0.05). BAs diminished decreased blood urea nitrogen (BUN) concentration, and 300 mg/kg BAs-supplemented diet has the most dramatic effect. Serum glucose (GLU) concentration lowered significantly with decreasing dietary BAs from 0 mg/kg to 100 mg/kg, and then increased significantly (P0.05). Compared with the control diet and 300 mg/kg BAs-supplemented diet, intestinal lipase activities and protease activities were higher in the groups fed with the diet supplemented with 100 mg/kg BAs (P0.05), but it had no significant difference with 200 mg/kg BAs-supplemented diet (P0.05). Dietary BAs levels had no influence on the intestinal amylase activities. The highest dietary nutrient apparent digestibility coefficients (ADC) was observed in 200 mg/kg BAs-supplemented diet, and the lowest ADC value was in the control group (P0.05). These results indicate that dietary BAs may improve growth performance, feeding efficiency and dietary apparent nutrient digestibility of bullfrog, and promote the catabolism of body lipid and protein retention, which raise the proportion of the edible part of bullfrog. Based on the results, 200 mg/kg bile acids supplementary level is recommended for bullfrog.