Efficacy And Tolerance Assessment Of Blie Acid In Micropterus Salmoides

Two experiments were conducted in our research. The effects of bile acid on growth performance, haematological profiles and antioxidant intestinal enzyme activity, bile acid content in the liver, intestines and gallbladder, the intestinal histology of large-mouth bass(Micropterus salmoides) was investigated, to determine the efficacy and tolerance assessment of bile acid in aquatic feeds.1. Efficacy assessment of bile acid in large-mouth bass dietsSix experimental diets was prepared with bile acid levels at 0、80、160、240、300、600 mg/kg, respectively. Each diet was fed to six replicates of 30 large-mouth bass(6.17 ± 0.02 g) for 70 days. he results showed that the addition of bile acid had significant effects on growth performance of large –mouth bass. 300 mg/kg bile acid improved SGR, WGR and FR significantly. 240, 300 mg/kg bile acid increased body fat of large-mouth bass significantly. 300 mg/kg bile acid increased SOD, T-AOC in plasma, and T-AOC in the liver, decreased MDA in the liver. With the increasing addition of bile acid, GSH-PX in plasma and liver increased significantly. In addition, total protein enhanced significantly with addition of bile acid at levels of 300 and 600 mg/kg. The addition of bile acid also improved amylase activity in anterior and mid intestines. Moreover, with the increasing addition of bile acid, bile acid in gall bladder increased significantly.On the basis of SGR, FR and TBA in the liver, the optimal dietary bile acid levels were 440.5 mg/kg,283.3 mg/kg and 253.8 mg/kg respectively using broken-line model. Variance analysis showed that large-mouth bass obtained best growth performance with bile acid level at 300 mg/kg. Within the scope mentioned above, bile acid decreased MDA in the liver and improved antioxidant activity. Bile acid significantly promoted fat metabolism via increasing HDL- C content in plasma. Moreover, the addition of bile acid enhanced amylase activity in intestines. To conclude, the recommended dose of bile acid in large-mouth bass diet was 253.8~283.3 mg/kg and the highest recommended dose was 300 mg/kg. 2. Tolerance assessment of bile acid added in large-mouth bass dietsFour experimental diets were prepared with bile acid levels at 0, 300, 600, 1500 mg/kg, in which 300 mg/kg was the highest recommended level, 600 and 1500 mg/kg were 2 and 5 fold, respectively. Each diet was fed to six replicates of 30 fish with initial body weight at 6.17 ± 0.02 g for 70 days. The results showed 300mg/kg bile acid level elevated the growth performance, plasma cholesterol metabolism,antioxidant and immune function, keep hepatic cell healthy significantly. As bile acid level is 2 fold than the highest recommended level, the growth performance is not different with D300 significantly. As bile acid level is 5 fold, the plasma MDA level is elevated than D300 significantly, and SOD, GSH-PX of plasma reach highest level(P<0.05).The 5 fold bile acid level could elevated the antioxidant performance abnormally, we believe that it is related to the bile acid deposition in the fish gallbladder. The tolerance assessment suggested that 2 fold of safety margin was obtained.