饲料中牛磺酸水平对红鳍东方鲀免疫及消化酶的影响

Effects of dietary taurine levels on immunity and digestive enzyme activities of redfin puffer Takifugu rubripes

为研究饲料中牛磺酸水平对红鳍东方鲀Takifugu rubripes免疫功能及消化酶的影响,选用初始体质量为(32.28±0.20)g的红鳍东方鲀幼鱼,随机分为5个处理组,每组设3个重复,配制牛磺酸添加量分别为0%(T1,对照)、0.5%(T2)、1.0%(T3)、2.0%(T4)和5.0%(T5)的试验饲料,分别投喂不同的处理组,试验在15个200 L方形聚乙烯水槽中进行,养殖试验共进行56 d。结果表明:添加了不同水平牛磺酸的饲料可显著提高红鳍东方鲀肝脏中总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)的活性(P<0.05),显著降低丙二醛(MDA)的含量(P<0.05),提高机体内自由基的清除能力,且在2.0%添加量时T-AOC达到峰值,而MDA含量下降到最低(P<0.05),SOD、CAT和GSH-PX在添加量为1.0%时酶活力达到峰值(P<0.05);肝脏AKP活力随饲料中牛磺酸含量的增加呈先升高后下降的趋势,在1.0%添加量时达到最大值(P<0.05),但牛磺酸对肝脏ACP活力无显著性影响(P>0.05);不同牛磺酸水平的饲料能显著提高红鳍东方鲀肠道脂肪酶活力,2.0%添加量时脂肪酶活力最高,且显著高于其他处理组(P<0.05),但牛磺酸添加量对肠道蛋白酶无显著性影响(P>0.05);1.0%、2.0%、5.0%添加量时红鳍东方鲀体表黏液溶菌酶活力显著高于对照组(P<0.05),在2.0%添加量时体表黏液溶菌酶活力达到最大值;通过对T-AOC、肠道消化酶和体表黏液溶菌酶这3个指标折线模型分析得出,红鳍东方鲀幼鱼饲料牛磺酸最适添加量为1.35～2.21 g/100 g(干饲料)。研究表明,饲料中添加牛磺酸可显著提高红鳍东方鲀的机体抗氧化及免疫能力,但过多的牛磺酸会导致抗氧化及免疫能力降低。

A feeding trial was conducted to investigate the effects of dietary taurine levels on immunity and digestive enzyme activities of juvenile redfin puffer Takifugu rubripes . Juvenile redfin puffer with initial body weight of ( 32.28± 0.20)g were reared in a 200 L square polyethylene tank at stocking density of 15 fish per tank and fed five diets containing taurine at a dose of 0%(group T1, control), 0.5%(group T2), 1.0%(group T3), 2.0%(group T4) and 5.0%(group T5) at water temperature of (23.0-24.5)℃ with triplication for 56 days. The results showed that there were significantly higher total antioxidant capacity(T-AOC), activities of superoxide dismutase(SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) and significantly lower malondialdehyde (MDA) level in liver of redfin puffer fed the diets supplemented with taurine than those in juveniles in control group( P <0.05), with the peak activities of SOD, CAT and GSH-PX in group T3 ( P <0.05). The liver alkaline phosphatase (AKP) activity was found to be significantly increased first and then decreased with increasing levels of dietary taurine, with the peak in group T3 ( P <0.05)and without significant difference in AKP activity ( P >0.05). Significantly higher lipases (LPS) activity was observed in intestine in group T4 than those in other groups ( P <0.05), with the maximal LPS activity in group T4. However, there was no significant difference in intestinal protease activity in various groups ( P >0.05). The redfin puffer juveniles had significantly higher lysozyme (LZM) activities in mucus in groups T3, T4, and T5 than that in control group ( P <0.05), with the maximum in group T4. Analysis of T-AOC, intestinal LPS and surface mucus LZM indicates that the optimal addition amount of taurine is 1.35-2.21 g/100 g(dry feed) in juvenile redfin puffer.