Effects Of Taurine On Growth Performance, Antioxidant Capacity And Lipid Metabolism Of Juvenile Grass Carp (Ctenopharyngodon Idella) Fed High-fat Diets

This study aimed at investigating the effects of taurine on growth performance, antioxidantcapacity and lipid metabolism of juvenile grass carp (Ctenopharyngodon idella) fed high-fatdiets.720healthy juvenile grass carp with initial body weight (45.13±2.78) g were reared in90L tank with stocking density of30fish/tank. Six semi-purified isonitrogenous (crude proteinwas30.5%) and isoenegetic (total energy was16.5MJ/kg) diets were formulated with asupplementation of taurine in high-fat treatments: treatment1was basal group (basal dietcontaining5.09%fat), treatment2was control group (high-fat diet containing8.25%fat,0mg/kg taurine), and the remaining four treatments were taurine treated groups (200,700,1200and1700mg/kg taurine were added on the high-fat diet, respectively). The trial was conductedwith quadruplicate group of fish in a freshwater running system at (26.5±1.0)℃for65days.The results showed that：(1) There were significant (P<0.05) high level of viscerosomatic index (VSI), lipid contentin muscle, malondialdehyde (MDA) content in hepatopancreas and serum, triglyceride（TG）,total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) in serum, arterialstiffness index (AI) and TG, TC in hepatopancreas in the control group compared with that in thebasal group. There were significant (P<0.05) low level of shell rate (ESR), activities ofsuperoxide dismutase (SOD) and catalase (CAT) in hepatopancreas and serum, activities ofcholesterol7α-hydroxylase (CYP7A1), hepatic lipase (HI) and total lipase (TL) inhepatopancreas in the control group compared with that in the basal group.(2) Compared with the control group, the700mg/kg taurine group significantly (P<0.05)increased weight gain rate (WGR), specific growth rate (SGR) and feed efficiency (FER); the1700mg/kg taurine group significantly (P<0.05) decreased the VSI. Supplementation of700-1700mg/kg taurine in the high-fat diets, ESR was significantly (P<0.05) increased and lipidcontent in muscle was significantly (P<0.05) decreased. Supplementation of200-1700mg/kgand700-1700mg/kg taurine in the high-fat diets, activities of SOD and CAT in hepatopancreaswere significantly (P<0.05) increased, respectively. Supplementation of1200mg/kg and700mg/kg taurine in the high-fat diets, activities of SOD and CAT in serum were significantly(P<0.05) increased, respectively. However, supplementation of700-1200mg/kg and200-1700mg/kg taurine in the high-fat diets, they significantly (P<0.05) decreased the content of MDA inhepatopancreas and serum, respectively. The level of TG in hepatopancreas and serum weresignificantly (P<0.05) reduced by supplementation of200-1700mg/kg,700and1700mg/kg taurine in the high-fat diet, respectively. Supplementation of700-1700mg/kg taurine in thehigh-fat diets, the level of TC in hepatopancreas and serum were significantly (P<0.05)decreased. Supplementation of700and1700mg/kg taurine in the high-fat diets, the level ofhigh density lipoprotein cholesterol（HDL-C）in serum was significantly (P<0.05) increased,while LDL-C in serum was significantly (P<0.05) decreased by supplementation of1200and1700mg/kg taurine in the high-fat diet. Compared with the control group, the taurine treatedgroups significantly (P<0.05) reduced AI. Compared with the control group, the700mg/kgtaurine group significantly (P<0.05) decreased activities of3-hydroxy-3-methyl glutaric acylcoenzyme A reductase（HMG-COAr）in hepatopancreas, and the1700mg/kg taurine groupsignificantly (P<0.05) increased activities of CYP7A1in hepatopancreas.Under the conditions of this trial, juvenile grass carp fed high-fat diets were significantlydecreased muscle quality, antioxidant capacity and significantly increased lipid level in serumand hepatopancreas. However, supplementation of700mg/kg taurine in the high-fat diets, therate of growth was significantly increased; supplementation of700-1700mg/kg taurine in its,muscle quality of fish was significantly improved and lipid level in serum and hepatopancreaswas significantly decreased; supplementation of700-1200mg/kg taurine in its, the antioxidantcapacity of juvenile grass carp was significantly increased. Overall consideration, under theconditions of this trial, the optimum dosage of taurine in the high-fat diets is700-1200mg/kg.