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

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。

EFFECTS OF DIETARY VITAMIN E AND L-CARNOSINE ON GROWTH PERFORMANCE,ANTIOXIDANT STATUS,NON-SPECIFIC IMMUNITY AND SERUM BIOCHEMICAL INDICES IN JUVENILE TURBOT (SCOPHTHALMUS MAXIMUS)

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).