VE和L-肌肽对大菱鲆幼鱼生长、抗氧化、非特异性免疫及血清生化指标的影响

摘要

实验以大菱鲆(Scophthalmus maximus)幼鱼[(14.00±0.02) g]为研究对象,采用2×4双因素设计,设2个VE水平(0和75 mg/kg)和4个L-肌肽水平(0、50、100和200 mg/kg),研究VE和L-肌肽对其生长、抗氧化、非特异性免疫及血清生化指标的影响。实验共分8组,每组3个重复,每个重复46尾鱼,实验周期为8周。结果显示：(1)在饲料中添加75 mg/kg VE显著提高了大菱鲆幼鱼增重率(WGR)和特定生长率(SGR)(P<0.05), L-肌肽添加量≤100 mg/kg对实验鱼生长性能无显著影响(P>0.05),添加量为200 mg/kg时鱼体WGR、SGR和蛋白质效率(PER)显著降低,饲料系数(FCR)显著升高(P<0.05)；(2)VE和L-肌肽对血清谷胱甘肽过氧化物酶(GSH-PX)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量及肝脏总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活性和MDA含量均具有显著的交互作用(P<0.05),在VE 75 mg/kg水平下, L-肌肽添加量为50和100 mg/kg时血清GSH-PX活性最高, L-肌肽添加量为100和200 mg/kg时血清CAT活性最高且与添加量为50 mg/kg差异不显著(P>0.05),添加100 mg/kg 肝脏T-AOC和SOD活性达到最高且50 mg/kg组的SOD与100 mg/kg组差异不显著(P>0.05),主效应结果显示, VE显著提高了血清T-AOC、SOD及肝脏CAT活性(P<0.05), L-肌肽显著提高了血清T-AOC(P<0.05)；(3)VE和L-肌肽对血清补体C3和LZM活性交互作用显著,在75 mg/kg VE水平下, L-肌肽添加量为50 mg/kg时,补体C3水平最高(P<0.05),主效应显示, VE和L-肌肽对血清总蛋白(TP)影响均不显著(P>0.05)；(4)添加VE显著降低了血清总胆固醇(TCHO)和甘油三酯(TG)含量(P<0.05),添加L-肌肽显著降低了血清TG含量,且在L-肌肽50 mg/kg时达到最低。综合考虑大菱鲆幼鱼[(14.00—39.43) g]的生长性能、抗氧化性能、非特异性免疫及血清生化指标得出,在实验配方条件下(鱼油70 g/kg,大豆卵磷脂10 g/kg),添加VE 75 mg/kg时, L-肌肽的适宜添加量为50 mg/kg。%A 2×4 factorial experiment (2 vitamin E×4 L-carnosine) was conducted to investigate the effects of dietary vitamin E (0 and 75 mg/kg) and L-carnosine (0, 50 mg/kg, 100 mg/kg and 200 mg/kg) on growth performance, antio-xidant status, non-specific immunity and serum biochemical indices in juvenile turbot. Eight diets were formulated and randomly allocated into triplicate groups of fish [initial body weight of (14.00±0.02) g] in 24 cylindrical tanks (H:80 cm×Φ70 cm, water depth 50 cm) with 46 fish per tank for an 8-weeks trial. Results showed that fish weight gain rate (WGR) and specific growth rate (SGR) were significantly enhanced by dietary vitamin E (P<0.05) but not by L-carnosine less than 100 mg/kg. However, WGR, SGR and protein efficiency ratio (PER) were depressed whereas feed conversion ra-tio (FCR) was elevated significantly by 200 mg/kg L-carnosine (P<0.05). Statistical interactions between vitamin E and L-carnosine were observed in serum glutathione peroxidase (GSH-PX), catalase (CAT) activities, malondialdehyde (MDA) content, liver total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and MDA (P<0.05). The highest GSH-PX activity was in the group of 50 mg/kg and 100 mg/kg L-carnosine, and the highest CAT activity was in the group of 100 mg/kg and 200 mg/kg L-carnosine and it showed no significant difference in group of 50 mg/kg (P>0.05). Liver T-AOC and SOD activities reached the top by 100 mg/kg L-carnosine and it showed no significant dif-ference by 50 mg/kg L-carnosine (P>0.05) or the 75 mg/kg vitamin E. Main effects analysis show that serum T-AOC, SOD and liver CAT activities were significantly elevated by dietary vitamin E (P<0.05), serum T-AOC was signifi-cantly elevated by dietary L-carnosine (P<0.05). Statistical interactions between vitamin E and L-carnosine were ob-served in serum complement C3 and LZM activities (P<0.05). Complement C3 reached the highest value in the group of 50 mg/kg L-carnosine and 75 mg/kg vitamin E (P<0.05). Serum total protein (TP) was not significantly affected by dietary vitamin E and L-carnosine (P>0.05). Serum total cholesterol (TCHO) and triacyglycerol (TG) contents were de-creased by vitamin E addition (P<0.05). Comparatively, TG was reduced by dietary L-carnosine with the lowest level by 50 mg/kg L-carnosine (P<0.05). These results suggest that 75 mg/kg vitamin E and 50 mg/kg L-carnosine is the best diet formulation (fish oil 70 g/kg, Soy lecithin 10 g/kg).