饲料硒含量对黄颡鱼幼鱼生长性能、抗氧化能力和脂肪代谢基因表达的影响

摘要

This experiment was conducted to investigate the effects of dietary selenium content on growth per⁃formance, antioxidant capacity and lipid metabolism gene expression of juvenile yellow catfish ( Pelteobagrus fulvidraco). A total of 450 juvenile yellow catfish with the initial body weight of (2.12±0.01) g were random⁃ly divided into 6 groups with 3 replicates per group and 20 fish per replicate. The fish in those groups were fed 6 isonitrogenous and isolipid experimental diets containing <0.05 (control group), 0.15, 0.23, 0.35, 0.47 and 0. 96 mg/kg selenium for 8 weeks, respectively. The results showed as follows: the weight gain rate ( WGR) increased firstly and decreased subsequently with dietary selenium content increasing, and the highest value appeared at the 0. 23 mg/kg selenium group, which was significantly higher than that in control group ( P<0.05) . The feed conversion rate ( FCR) exhibited an opposite trend to the WGR, and the 0.23 mg/kg se⁃lenium group had the lowest value, which was significantly lower than that in control group (P<0.05). The survival ratio in all groups was 100%. The highest whole body crude protein content was found in the 0.35 mg/kg selenium group, which was significantly higher than that in control group and 0.23 mg/kg seleni⁃um group ( P<0.05) . The whole body crude lipid content in control group was significantly lower than that in 0.15, 0.47 and 0.96 mg/kg selenium groups ( P<0.05) , but the whole body moisture content in control group was significantly higher than that in 0.15, 0.35, 0.47 and 0.96 mg/kg selenium groups ( P<0.05) . The plas⁃ma cholesterol ( CHO) content in 0.23 mg/kg selenium group was the lowest, and was significantly lower than that in control group ( P<0.05) . The whole body selenium content and liver glutathione peroxidase ( GPx) ac⁃tivity were enhanced with dietary selenium content increasing, and presented a dose⁃response relationship. The liver superoxide dismutase ( SOD) activity was firstly increased and then decreased with dietary selenium con⁃tent increased from <0. 05 to 0. 47 mg/kg, and then was increased again when dietary selenium content was 0.96 mg/kg. The relative expression levels of lipoprotein lipase ( LPL) and lipoprotein lipase ( FAS) mRNA in control group were significantly lower than those in 0.23 mg/kg selenium group ( P<0.05) . Using WGR as the evaluation index, the suitable dietary selenium content of juvenile yellow catfish is estimated to be 0.20 mg/kg by nonlinear regression analysis.%本试验旨在研究饲料中硒含量对黄颡鱼幼鱼生长性能、抗氧化能力和脂肪代谢基因表达的影响。选用初始体重为（2．12±0．01） g的黄颡鱼幼鱼450尾，随机分为6组，每组设3个重复，每个重复25尾幼鱼，分别投喂硒含量＜0．05（对照组）、0．15、0．23、0．35、0．47和0．96 mg／kg的6种等氮等脂试验饲料，饲养期为8周。结果显示：黄颡鱼的增重率随着饲料硒含量的升高呈现先升高后降低的趋势，在饲料硒含量为0．23 mg／kg 时达到最高，显著高于对照组（ P＜0．05）。饲料系数的变化趋势与增重率相反，在饲料硒含量为0．23 mg／kg时达到最低，显著低于对照组（P＜0．05）。存活率各组均为100％。全鱼粗蛋白质含量在饲料硒含量为0．35 mg／kg的组最高，显著高于对照组和饲料硒含量为0．23 mg／kg的组（ P＜0．05）。对照组全鱼粗脂肪含量显著低于饲料硒含量为0．15、0．47和0．96 mg／kg的组（ P＜0．05），而对照组全鱼水分含量则显著高于饲料硒含量为0．15、0．35、0．47和0．96 mg／kg的组（ P＜0．05）。血浆胆固醇含量在饲料硒含量为0．23 mg／kg的组最低，显著低于对照组（ P＜0．05）。全鱼硒含量和肝脏谷胱甘肽过氧化物酶（ GPx）活性随着饲料硒含量的增加而升高，二者与饲料硒含量呈正剂量效应关系。肝脏超氧化物歧化酶（SOD）活性随着饲料硒含量由＜0．05 mg／kg升高到0．47 mg／kg表现为先升高再降低，而后在饲料硒含量为0．96 mg／kg时又出现升高。对照组肝脏脂蛋白脂酶（ LPL）和脂肪酸合成酶（ FAS） mRNA的相对表达量显著低于饲料硒含量为0．23 mg／kg的组（ P＜0．05）。以增重率为评价指标，通过非线性回归分析计算出黄颡鱼幼鱼饲料中硒的适宜含量为0．20 mg／kg。