细鳞鲑幼鱼n-3 HUFA需求量的研究

为确定细鳞鲑(Brachymystax lenok)n-3 HUFA需求量以减少鱼油使用和降低养殖成本,研究饲料中不同水平的n-3 HUFA对细鳞鲑的生长性能、体成分和肌肉脂肪酸组成的影响。以脱脂鱼粉、脱脂豆粕、明胶和酪蛋白为主要蛋白源,通过调节饲料中的猪油和浓缩油EPA、DHA水平,使饲料n-3HUFA的含量分别达到0.25%、0.50%、0.75%、1.00%、1.25%、1.50%,配制出6种等氮等能的试验饲料(D 0.25、D 0.50、D 0.75、D1.00、D 1.25和D 1.50),分别投喂细鳞鲑幼鱼(60.0 g±2.8 g)84 d。结果显示:饲料中n-3HUFA不同水平对细鳞鲑成活率和饲料系数没有显著影响,但是显著影响了其末重(FW)、增重率(WGR)和特定生长率(SGR)。随着添加饲料中n-3HUFA水平的升高,FW、WGR和SGR有先升高后下降的趋势,且3者在饲料中n-3HUFA水平为0.75%均最大。随着饲料中n-3 HUFA水平的升高,鱼肌肉18∶1n-9的含量逐渐下降,而22∶6n-3的水平相应升高。结果表明,以WGR为评价指标时,用二次曲线模型推测出细鳞鲑对饲料n-3 HUFA的需求量约为0.69%。

Requirement of dietary n-3 highly unsaturated fatty acids for juvenile Brachymystax lenok

In order to determine the demand of n-3 highly unsaturated fatty acids (HUFA),to reduce fish oil content in feed and reduce the cost of culture,the experiment was evaluated to the effects of different dietary levels n-3 HUFA on growth performance,body composition and fatty acid composition of muscle.The content of n-3HUFA in feed were 0.25,0.50,0.75,1.00 and 1.25％ by adjusting the contents of EPA and DHA in feedstuff and defatted fishmeal,defatted soybean meal,gelatin and casein as the main protein source (D 0.25,D 0.50,D 0.75,D 1.00,D 1.25,and D 1.50).Fish were fed on six experimental feeds (60.0 ± 2.8 g) for 84 d.The results showed that n-3HUFA had no significant effect on survival rate and feed conversion rate (P ＞ 0.05),but had significant effects on final weight (FW),weight gain rate (WGR) and specific growth rate (SGR).FW,WGR and SGR increased firstly and then decreased with increasing dietary n-3HUFA levels,and maximum value of FW,WGR and SGR were obtain at D 0.75 group.The content of muscle 18∶1 n-9 gradually decreased,while the level of 22∶6n-3 increased accordingly.In summary,WGR as an evaluation index,the requirement for n-3 HUFA of trout is about 0.69％ of diet by the second-order polynomial regression analysis.