微粒饲料替代生物饵料对大黄鱼稚鱼生长、存活和消化酶活力的影响

Effects of substitution of live prey by microdiet on growth,survival and activities of digestive enzymes of larval Pseudosciaena crocea

以初始体重为（1．93±0．11）mg的大黄鱼稚鱼（12日龄）为实验对象，以微粒饲料（micro-diet，MD）分别替代0％、25％、50％、75％和100％生物饵料（live prey，LP），探讨微粒饲料替代生物饵料对大黄鱼稚鱼生长、存活、体成分和消化酶活力的影响。30d的摄食生长实验表明：微粒饲料替代生物饵料显著影响大黄鱼稚鱼的生长、存活、体成分和消化酶活力。当微粒饲料替代50％和75％生物饵料时，两组间的特定生长率（SGR）差异不显著（P〉0．05），但均显著高于100％替代水平（P〈0．05）；同时，75％替代水平SGR显著高于0％和25％替代水平（P〈0．05）。存活率在各处理组间的差异关系与SGR的变化趋势类似。鱼体粗蛋白含量随替代水平的升高有下降的趋势，其中50％、75％和100％替代水平鱼体粗蛋白含量显著低于0％和25％替代水平（P〈0．05），而鱼体粗脂肪含量变化趋势与之相反。当微粒饲料替代100％生物饵料时，其胰段和肠段淀粉酶活力显著高于其余各处理组（P〈0．05），而其余各处理组之间淀粉酶活力差异均不显著；微粒饲料替代生物饵料对各处理组蛋白酶活力无显著影响。由此可以看出，大黄鱼苗种生产中，在12日龄以后使用优质微粒饲料替代50％～75％的生物饵料是可行的。

A 30-day feeding experiment was conducted in tanks to examine the effects of substitution levels of live prey （LP） by micro-diet （MD） on growth, survival, body composition and digestive enzymes of large yellow croaker larvae, Pseudosciaena crocea. Five treatments with microdiet replacing 0% （0% MD）, 25% （25% MD）, 50% （50% MD）, 75% （75% MD） and 100% （100% MD） of live prey, were used. Each treatment was randomly assigned to triplicate groups of tanks, and each tank was stocked with 3 500 larvae. The results showed that the substitution of LP by MD significantly influenced the growth, survival, body composition and digestive enzymes of large yellow croaker larvae. The specific growth rates （SGR） of 50% MD and 75 % MD were significantly higher than those of 100% MD （P〈0.05）, and the SGR of 75% MD were significantly higher than those of 0% MD and 25% MD （P〈0.05）. However, no significant differences were observed in SGR between 50% MD and 75 % MD. The changes of survival rates among different tested groups followed the similar pattern as that of SGRs. Carcass protein content declined with the increasing of the substitution levels, and carcass protein contents of 50% MD, 75% MD and 100% MD were significantly lower than 0% MD and 25% MD （P〈 0.05）. On the contrary, carcass lipid content increased with the increasing of substitution levels. The amylase specific activities of 100% MD were significantly higher than those of the other groups （P〈0.05）, but trypsin specific activities were not significantly different among dietary treatments. Therefore, these results indicate that substituting 50%-75% of LP by MD after 12-day hatching in fry production of large yellow croaker is appropriate.