核苷酸对大黄鱼生长性能、肠道形态和抗氧化能力的影响

为探究饲料中添加核苷酸对大黄鱼生长性能、肠道形态和抗氧化能力的影响,实验选取初始体质量为(7.71±0.02)g的大黄鱼幼鱼为研究对象,设置2个对照组,即高鱼粉对照组FM(鱼粉含量为45.0%)和低鱼粉对照组N0(鱼粉含量为31.5%),在低鱼粉对照组基础上分别添加0、75、150、300、600和1 000 mg/kg的核苷酸,共配制出7种等氮等脂饲料,在海水浮式网箱中进行为期63 d的养殖实验。结果表明:饲料中添加核苷酸对大黄鱼的存活率、饲料效率、摄食率、鱼体组成和形体指标没有显著影响(P0.05);但增重率随着核苷酸添加量的增加呈先升高后下降趋势,在添加量为300~600 mg/kg时显著高于其他处理组(P0.05)。随着核苷酸添加量的增加,血清中超氧化物歧化酶(SOD)和总抗氧化力(T-AOC)的活力呈先升高后下降的趋势,并在300 mg/kg时显著高于低鱼粉对照组(P0.05)。核苷酸对大黄鱼肠道肌肉层厚度和微绒毛高度有显著影响(P0.05),分别在添加量为150和300mg/kg时出现最大值;而对肠道褶皱高度无显著影响(P0.05)。结果表明,饲料中添加核苷酸能促进大黄鱼生长,改善肠道形态结构和增强机体的抗氧化能力。以增重率为指标,利用折线模型计算得到大黄鱼幼鱼饲料中核苷酸的适宜添加量为194.91 mg/kg。

Effects of dietary nucleotides on growth performance,intestinal morphology and anti-oxidative capacities of large yellow croaker(Larimichthys crocea)

The present study was conducted to analyze the effects of dietary nucleotides on growth performance,intestinal morphology and anti-oxidative capacitiesof juvenile large yellow croaker (Larmichthys crocea)(initial weight: 7.71±0.02g).Two control diets were set. They were high fishmeal (FM, 45.0%) supplemented diet and low fishmeal (N0, 31.5%) supplemented diet, respectively. Based on the latter, five graded levels of nucleotides were added. They were 75, 150, 300, 600 and 1000 mg/kg, respectively. After the 9week growth trial, results showed that survival rate, feed efficiency, feed intake and body composition of the animals were no significantly influenced by dietary nucleotideslevels (P>0.05).Weight gain rates (WGR) of fish fed the diets with 300or 600mg/kg of nucleotides were significantly higher than those in the other groups (P<0.05).Dietary nucleotides significantly affected the total anti-oxidative capacity(T-AOC) and superoxide dismutase(SOD)activity in serum(P<0.05).Values of T-AOC and SOD increased fist, and then declined as the dietary nucleotides levels increased. The highest value of these two parameters was found in the treatment with 300 mg/kg of dietary nucleotides. Dietary nucleotide significantly increased microvillus height (HMV)and the thickness of the muscular layer(TML) in the proximal intestine(P<0.05).The HMV in intestine of fish fed diet with 300mg/kg of nucleotides was higher than that in the control group. The TML in intestine of fish fed diet with150 mg/kg of nucleotides was higher than that in the control group. There was no significant difference in folds height(HF) ofintestinal among the all groups (P>0.05). In conclusion, dietary nucleotides can improve the growth of the large yellow croaker. Meanwhile, it can also increase the anti-oxidative capacity and improve the intestinal morphology. Based on the data of WGR,the broken-line analysis showed that the optimal level of dietary nucleotides was 194.91mg/kg.