| The present study aimed to determine the optimal vitamin A,C and E requirement of juvenile silver sillago,Sillago sihama fed different dietary vitamin levels through a8-week feeding experiment.The main contents and results were showed as follows:1.A 8-week growth trial was conducted to investigate vitamin A requirement for sillago sihama(S.sihama)(2.02±0.15 g)through the effect on growth,immunity,oxidation resistance,biochemical and digestion indices.Seven diets containing 7 levels of vitamin A(362,751,1141,2202,4335,8230 and 18932 IU/kg,respectively),with defatted white fish meal and vitamin-free casein serving as protein sources and soybean lecithin oil and fish oil as lipid sources,were fed to juvenile S.sihama.The results indicated that proper dietary vitamin A level increased weight gain(WG),specific growth rate(SGR),protein efficiency ratio(PER),survival rate(SR)and hepatosomatic index(HSI),decreased feed conversion ratio(FCR)(P<0.05);increased hepatic lysozyme(LZM),alkaline phosphatase(AKP)and acid phosphatase(ACP),intestinal LZM and ACP activities(P<0.05);increased hepatic and intestinal total antioxidant capacity(T-AOC),catalase(CAT),glutathion peroxidase(GPx)activities(P<0.05),decreased malondialdehyde(MDA)content(P<0.05);increased hepatic glucose(GLU),triglyceride(TG),cholesterol(TC),high density lipoprotein cholesterol(HDL-C)content(P<0.05);increased intestinal amylase,pepsin,trypsin and sodium potassium ATPase(Na~+-K~+ATP)activities(P<0.05).Based on regression analysis for WG,Na~+-K~+ATP,hepatic T-AOC and vitamin A concentration,the optimal requirement of dietary vitamin A in juvenile S.sihama was estimated to be 2437,2202,4685,4564 IU/kg diet,respectively.2.A 8-week growth trial was conducted to investigate vitamin C requirement for sillago sihama(S.sihama)(2.33±0.02 g)through the effect on growth,immunity,oxidation resistance and NF-E2-related factor 2-Kelch-like ECH-associated Protein 1(Nrf2-Keap1)singnling pathway related genes expression.Six diets containing 6 levels of vitamin C(5,16,27,65,122,233 mg/kg,respectively),with steam white fish meal,vitamin-free casein and gelatin serving as protein sources and corn oil,fish oil and soybean lecithin oil as lipid sources,were fed to juvenile S.sihama.The results indicated that proper vitamin C supplementation in diets increased WG,SGR,feed intake(FI)and PER,decreased HSI(P<0.05);increased hepatic total immunoglobulin(IgM),complement 3(C3),complement 4(C4)and AKP activity(P<0.05);increased hepatic and intestinal T-AOC,CuZnSOD,CAT,GPx and hepatic glutathione S-transferase(GST)activities,decreased hepatic MDA and lipid peroxidase(LPO)contents(P<0.05);increased genes expression of Nrf2,Keap1,CAT,GST,GPx,GR,CuZnSOD and MnSOD in liver and intestine.Based on regression analysis for PER,IgM,intestinal CuZnSOD and hepatic vitamin C concentration,the optimal requirement of dietary vitamin C in juvenile S.Sihama was estimated to be 98.33,139.03,104.23 and 143.69mg/kg.3.A 8-week growth trial was conducted to investigate vitamin E requirement for sillago sihama(S.sihama)(2.14±0.02 g)through the effect on growth,immunity,oxidation resistance and Nrf2-Keap1 singnling pathway related genes expression.Six diets containing 6 levels of vitamin E(4,14,22,47,95 and 198 mg/kg,respectively),with defatted white fish meal,vitamin-free casein and gelatin serving as protein sources and corn oil,fish oil and soybean lecithin oil as lipid sources,were fed to juvenile S.sihama.The results indicated that proper vitamin E supplementation in diets increased WG,SGR,FI and PER,decreased FCR(P<0.05);increased hepatic IgM,AKP and LZM(P<0.05);increased CuZnSOD,CAT,GPx and GST activities in liver and intestine,increased intestinal T-AOC,decreased hepatic LPO and MDA contents(P<0.05);up-regulated Nrf2,Keap1,CAT,GST,GPx,GR,CuZnSOD and MnSOD genes expression in liver and intestine(P<0.05).Based on regression analysis for WG,IgM,hepatic MDA,the optimal requirement of dietary vitamin E in juvenile S.Sihama was estimated to be 100.37,116.37 and 114.9 mg/kg. |
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