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.