Effect of taurine supplemention at different dietary lipid levels on growth performance, body composition, hepatopancreas biochemical index and antioxidant capacity of juvenile common carp (Cyprinus carpio)

This experiment was aimed to investigate the effects of taurine supplemention at different dietary lipid levels on growth performance, body composition,hepatopancreas biochemical index and antioxidant capacity of juvenile Cyprinus carpio. A total of 720 healthy juvenile C. carpio with average initial body weight of (1.17±0.01) g were randomly divided into eight treatments (3 replicates per treatment and 30 carp each replicate).Eight isonitrogenous and isoenergetic experimental diets were formulated with the graded taurine levels (0,400, 800 and 1 600 mg/kg dry diet, respectively) in dietary lipid level of 4.65% and 10.22% respectively. The experiment lasted for 56 days. The results showed that the weight gain ratio (WGR), the specific growth ratio (SGR) and protein efficiency ratio (PER) of juvenile C. carpio in 4.65% lipid group were higher than 10.22% lipid group, at the same time, the feed conversion ratio (FCR) was the lower than 10.22% lipid group when taurine were not added. The WGR、SGR、PER were significantly improved, while the FCR were significantly decreased when taurine were added. The WGR、SGR、PER of juvenile C. carpio initially increased with increasing dietary taurine levels and then towards stability. Conversely, the feed conversation ratio (FCR) first decreased and then towards stability. The WGR, SGR, PER were all the highest when the dietary taurine level was 800 mg/kg, at the same time, the FCR was the lowest. The WGR、SGR、PER were significantly higher and the FCR were significantly lower in the 10.22% lipid group than 4.65% lipid group when taurine was added more than 800 mg/kg. The total cholesterol (TCH) and triglyeride (TG) in hepatopancreas were gradually decreasing with taurine level increasing. However, there was no significant difference in the 4.65% lipid group, while the difference in the 10.22% lipid group was significant, and the condition factor (CF) of juvenile C. carpio first increased with increasing dietary taurine levels and then towards stability, at the same time, the hepatosomatic index (HIS) and viscerosomatic index (VSI) first decreased and then lowards stability. The crude protein in whole body first increased with increasing dietary taurine levels and then owards stability,while the crude lipid first decreased and then towards stability. With the increase of dietary taurine level, the activities of superoxide dismutase (SOD), catalase (CAT) in hepatopancreas first increased then decreased, the activities of SOD and CAT were all the highest when the dietary taurine level was 800 mg/kg. At the same time, the content of malondialdehyde (MDA) in hepatopancreas was gradually decreasing, and the the content of MDA was the lowest when the dietary taurine level was 1 600 mg/kg. Results of above show that the appropriate dietary taurine level (800–1 600 mg/kg) could effectively improve the utilization of dietary lipid, promote the growth, reduce the lipid deposition, improve the muscle quality and the antioxidant capacity of C. carpio.