不同转食策略对胭脂鱼仔鱼和稚鱼生长及存活率的影响

为研究不同转食策略对胭脂鱼仔鱼和稚鱼生长和存活率的影响,实验采用2种转食策略投喂初始体质量为(9.50±0.84)mg的胭脂鱼仔鱼到其60 dph(days post hatching),(1)按转食起始点不同分为3组,转食起始点分别为15dph(W15)、20 dph(W20)和25 dph(W25),结果显示:3个组的存活率均达8 0%以上,W20组存活率最高,为91.21%±1.93%,但差异不显著;各组特定生长率(SGR)整体呈下降趋势,全部转食饲料到实验结束即35~60 dph时间段内,W20和W25的SGR显著高于W15,且这2组差异不显著;W25的全长和体质量最高,W15最低且显著低于另外2组;W20和W25的体质量差异不显著;(2)在20 dph开始转食,按转食过渡时间长短不同分为3组,分别是转食过渡时间为5 d(W20-1)、10 d(W20-2)和15 d(W20-3),结果显示:W20-2和W20-3的存活率不存在显著性差异,分别为95.73%±0.60%和91.21%±1.93%,显著高于W20-1;各组SGR整体呈下降趋势,全部转食饲料到实验结束即35~60 dph时间段内,W20-2和W20-3的SGR显著高于W20-1,且这2组差异不显著;W20-3全长和体质量均显著高于其他2组。以上结果表明,延后转食时间起始点和延长转食过渡时间,其转食后的SGR、全长和体质量有增大趋势,但在不显著影响鱼苗生长和存活的前提下,应尽量缩短生物饵料投入的时间,降低养殖成本。因此本研究中,转食起始点为20 dph,转食过渡时间为10 d是最适宜胭脂鱼仔鱼的转食策略。

Effects of different weaning strategies on the growth and survival rate in larvae and juvenile of Chinese sucker, Myxocyprinus asiaticus

In order to study the growth and survival rate of the Chinese sucker (Myxocyprinus asiaticus) under different weaning strategies, two weaning strategies were adopted to feed the M. Asiaticus, which is from larvae (9.50±0.84) mg to 60 days post hatching (dph). (1) Three groups were divided depending on different weaning starting points, 15 dph (W15), 20 dph (W20) and 25 dph (W25), respectively, and each group was performed in triplicate. The results showed the survival rates of all three weaning groups were more than 80%. The W20 group had the highest survival rate 91.21%±1.93%, but there was no significant difference among them. The specific growth rate (SGR) of each group was decreasing. In 35-60 dph period all groups were fed micro-diet until the end of the experiment, the SGR of W20 and W25 groups was significantly higher than that of W15 group. The difference between the two groups was not significant. The W25 group had the highest total length and body weight, which was significantly higher than that of W20 group. The body weight of the W20 group and W25 group didn't show significant between each other. (2) Beginning to wean at 20 dph, we divided the fish into three groups depending on different weaning transition time, 5 d (W20-1), 10d (W20-2) and 15d (W20-3) in W20 group, respectively. Each group was performed in triplicate. The results showed that:the survival rate of W20-2 and W20-3 groups was 95.73%±0.60% and 91.21%±1.93%, respectively, there was no significant difference. The survival rates of this two groups were higher than that of W20-1 group. The SGR of each group was decreasing. In 35-60dph period all groups were fed micro-diet until the end of the experiment, the SGR of W20-2 and W20-3 groups was significantly higher than W20-1 group. The difference between the two groups was not significant. The length and body weight of W20-3 group were significantly higher than those of the other two groups. These results indicated that delaying the starting point and extending the transition time of weaning would promote the SGR after weaning, total length and body weight of larvae Chinese sucker. But we should try our best to shorten the feeding time of organism food prey to reduce the cost as much as possible if it has not significant impact on the growth and survival of the larvae Chinese sucker. In conclusion, starting weaning at 20 dph and a 10-day transition time of weaning are the most appropriate weaning strategy for M. asiaticus in this experiment.