饲料中脂肪含量对七彩神仙鱼幼鱼生长和消化的影响

The effect of dietary fat levels on growth and digestibility in juvenile discus Symphysodon aequifasciata

在水温29.0±1.0℃下,将140日龄、体质量8～10g的七彩神仙鱼(Symphysodon aequifasciata)幼鱼放入室内54cm×40cm×28cm的水箱中,投喂以鱼粉和豆粕为蛋白源(粗蛋白45.0%)、以豆油为脂肪源配制的5种脂肪水平(10.21%、12.02%、17.17%、21.0%,和22.14%)的饲料。90d的饲养表明,七彩神仙幼鱼的成活率变化在96.67%～100.0%之间,各组间差异不显著(P>0.05)。随饲料中脂肪含量的增加,鱼的特定生长率(SGR)、蛋白质效率(PER)和增重率均先增加而后降低;摄食含12.02%脂肪饲料的鱼SGR、PER和增重率极显著地高于摄食含10.22%和22.14%脂肪饲料的鱼(P<0.001),而当鱼摄食含17.17%和21.05%脂肪的饲料时,SGR、PER和增重率与摄食含12.02%脂肪饲料的鱼差异不显著(P>0.05)。当饲料中脂肪含量为12.02%时,鱼对饲料中蛋白质的消化率最高;摄食含脂肪为10.22%、12.02%和17.17%的饲料时,对饲料蛋白的消化率差异不显著(P>0.05)。实验表明,七彩神仙鱼幼鱼饲料中适宜脂肪含量在12.02%～17.17%之间。

A feeding experiment was conducted to evaluate the effect of different dietary fat levels on growth performance and digestibility in discus Symphysodon aequifasciata juveniles weighing 8-10 g. The juveniles were stocked into 15 plastic tanks of each 54cm×40cm×28cm and fed isonitrogenous semi-purified diets containing 45.0% protein with fish meal, and soybean meal as protein sources, and lipid levels of 10.21%, 12.02%, 17.17%, 21.0%, and 22.14% with soybean oil as lipid sources for 90 days at water temperature of 29.0±1.0℃. During the experiment, survival ranged from 96.67% to 100.0% without significant different （P 〉 0.05）. The specific growth rate （SGR）, protein efficiency ratio （PER）, and relative weigh gain （RWG） increased first and then decreased as the dietary fat levels increased. The juveniles fed the diets containing 12.02% fat had very significantly higher SGR, PER, and RWG than the fish fed the dietary fat levels of 10.22% and 22.14% （P〈0.001）.There were no significant differences in SGR, PER, and RWG in the juveniles fed the diets containing 17.17% and 21.05% compared with the fish fed the dietary fat levels of 12.02% fat （P〉 0.05）. The maximal protein digestibility was observed in the juveniles fed the diets containing 12.02% fat and there were no significant differences in protein digestibility in the fish fed the dietary fat levels of 10.22%, 12.02% and 17.17% （P〉0.05）, indicating the optimal dietary fat ranged from 12.02% to 17.17% for discus juveniles.