饲料中糖/脂肪比例对瓦氏黄颡鱼生长、饲料利用、血糖水平和肝脏糖酵解酶活力的影响

摘要

An 8-week feeding trial was conducted to evaluate the effects of dietary carbohydrate-to-lipid (CHO : L) ratio on growth performance, feed utilization, plasma glucose and key glycolytic enzyme activities of juvenile darkbar-bel catfish (Pelteobagrus vachelli). Five isonitrogenous (crude protein 40%) and isoenergetic (19 MJ/g) diets were formulated to contain with graded levels of CHO : L ratios (0.75—6.53). Each diet was randomly assigned to triplicate tanks (50 L), and each tank was stocked with 40 fish with initial body weight of (4.20±0.02) g. The specific growth rate (SGR) increased first and then decreased with the increasing dietary CHO : L, and reached to the highest in fish fed diets with CHO : L of 3.55, which was significantly higher than those of fish fed the diets with 0.75 and 6.53 ratios (P<0.05). Feed efficiency (FE) and protein efficiency ratio (PER) showed no significant difference among treatments with CHO : L of 1.30—3.55, but FE and PER significantly decreased at CHO : L of 0.75 and 6.53 respectively (P<0.05). No significant difference was observed in the HSI and VSI of the darkbarbel catfish among dietary treatments (P>0.05). The crude protein of fish whole body increased first and then decreased with the increasing dietary CHO : L, and reached to the highest in fish fed diets with CHO : L of 3.55, which was significantly higher than that at CHO : L of 0.75 (P<0.05). The crude lipid of fish whole body decreased with the increasing dietary CHO : L significantly (P<0.05). There was no significant difference in the plasma glucose and total cholesterol among dietary treatments (P>0.05). Plasma triglycercide concentrations increased significantly with the increasing dietary CHO : L (P<0.05). Hepatic glucokinase (GK) activities increased first and then decreased with the increasing dietary CHO : L, and reached to the highest at the CHO : L of 3.55, which was significantly higher than those at CHO : L of 0.75 (P<0.05). However, no significant difference was observed in activities of hepatic hexokinase (HK), pyruvate kinase (PK) and 6-phosphofructo-l-kinase activity (PFK-1) among dietary treatments (P>0.05). Based on second-order polynomial regression analysis of SGR against dietary CHO : L ratios, a CHO : L ratio of 4.06 was proved to be optimal for the growth of juvenile darkbarbel catfish.%以初始体重(4.20±0.02) g 的瓦氏黄颡鱼(Pelteobagrus vachelli)幼鱼为实验对象,在流水系统中进行为期8 周的摄食生长实验,探讨饲料中糖与脂肪比例(CHO∶L)对其生长、饲料利用、血糖水平和糖酵解酶活力的影响.饲料等氮(粗蛋白40%)等能(19 MJ/g),CHO∶L 梯度为0.75-6.53.每种饲料随机投喂3 桶鱼,每桶(50 L)放养40 尾鱼.实验结果表明随着CHO∶L 升高,瓦氏黄颡鱼特定生长率(SGR)先升高后降低,当CHO∶L 为3.55 时,SGR 达最大,显著高于CHO∶L 为0.75 和6.53 时的值(P<0.05).饲料效率(FE)和蛋白效率(PER)在CHO∶L 为1.30-3.55 区间内都没有显著差异,但当CHO∶L 为0.75 或6.53 时,FE 和PER 的值都显著降低(P<0.05).脏体比(VSI)、肝体比(HSI)在各处理组间无显差异(P>0.05).随CHO∶L 的增加,全鱼粗蛋白含量先增加后降低,且在CHO:L 为3.55 时达到最大值,且显著高于CHO:L 为0.75 时的值(P<0.05).而全鱼粗脂肪含量随CHO∶L 增加而显著减少(P<0.05).血糖和血浆总胆固醇水平在各处理组间无显著差异(P>0.05),而血浆甘油三酯水平随CHO∶L 的增加而显著增加(P<0.05).随CHO∶L 的增加,瓦氏黄颡鱼肝脏葡萄糖激酶(GK)活力先增加后降低,且在CHO∶L 为3.55 时活力最大,显著高于CHO∶L 为0.75 时的值(P<0.05).肝脏己糖激酶(HK)、丙酮酸激酶(PK)和磷酸果糖激酶(PFK-1)活力在各处理组间没有显著差异(P>0.05).用二次多项回归模型拟合特定生长率和CHO∶L 的关系,得到饲料最适CHO∶L 为4.06.