延迟投饵对半滑舌鳎仔鱼生长、存活和体成分的影响

Effects of delayed first feeding on growth, survival and biochemical composition in tongue sole Cynoglossus semilaevis larvae

中文关键词: 延迟投饵  半滑舌鳎  仔鱼  生长  体成分  存活率

英文关键词: Delayed feeding  Cynoglossus semilaevisLarvae  Growth  Biochemical composition  Survival rate

中文摘要:

      以半滑舌鳎Cynoglossus semilaevis仔鱼为研究对象，将其分为4个处理组，分别在孵化后第3天(对照组)、延迟1 d(D1组)、延迟2 d(D2组)和延迟3d(D3组)投喂轮虫，探讨延迟投饵对半滑舌鳎仔鱼生长、存活和体成分的影响。实验水温21~22 ℃，盐度为31.00，试验周期为15 d。结果显示，仔鱼于孵出后第3天进入混合营养期，从第4天开始加速生长，第5天进入外源性营养期。延迟投饵2 d，会使仔鱼的干重、粗蛋白和粗脂肪的含量明显低于对照组(P<0.05)。随着投饵天数的延迟，仔鱼的存活率也随之降低。在仔鱼开口后4 d内，各组死亡率差异不大；开口后第6天(孵化后第8 天)，仔鱼死亡率呈现明显差异。在孵化后第10天，延迟投饵3 d的仔鱼几乎完全死亡。

英文摘要:

      The effect of delayed feeding in early development stage on growth, survival and biochemical composition in tongue sole Cynoglossus semilaevis larvae was examined. Larvae were divided into four groups, each with 500 larvae (three replicates). At the water temperatures of 21~22 ℃ and salinity of 31.0, initial feeding of the control group with rotifer began at 3 days post-hatch (dph), the feeding of the other groups began at 4 dph (delayed feeding 1 day, D1), 5 dph (D2) and 6 dph (D3), respectively. The results showed that the mixed feeding stage for the larvae was at 3 dph. It was at 4 dph when the growth of larvae began accelerating. The yolk sac was almost completely absorbed at 5 dph, which suggested for an onset of complete exogenous feeding. After the 15d experiment, significant difference was observed only in dry weight between the control and the D1 larvae. The total length, dry weight, protein content and lipid content of D2 larvae were significantly lower than the control larvae (P<0.05). The survival rate of larvae decreased corresponding to the delay in initial feeding time. There was no significant difference found in mortality among all treatments within 4 days after mouth-opening. While 6 days after mouth-opening, the difference was much more significant. The morality of D3 larvae reached almost 100% at 10 dph.