延迟首次投喂对胭脂鱼仔鱼生长、摄食及消化酶活性的影响

Effects of delayed first feeding on the growth,feeding and activities of digestive enzyme of the Myxocyprinus asiaticus larvae

在水温（19±0．5）℃条件下，为研究不同饥饿时间对胭脂鱼仔鱼生长、摄食及消化酶活性的影响，设定两个实验：实验一，设置完全饥饿组（S）和正常摄食组（C）；实验二，设置延迟0（对照组）、1、3、5、7、9和11d投喂组，分别记作D0、D1、D3、D5、D7、D9和D11。实验历时29d。结果显示：（1）孵化后7d胭脂鱼仔鱼初次摄食，14d时卵黄物质耗尽，27d进入不可逆点期（PNR），在抵近PNR时，胸角特征明显，死亡率显著增加；（2）恢复摄食后，D1和D3组仔鱼体质量与D0组无显著差异，表现出完全补偿生长效应；（3）在饥饿1-7d过程中，胭脂鱼仔鱼的胰蛋白酶和淀粉酶活性显著下降（P〈0．05），随着饥饿时间的延长，饥饿9～11d仔鱼的胰蛋白酶和脂肪酶活性显著上升。恢复摄食后19日龄时，胰蛋白酶活性随饥饿时间的延长呈先上升后下降的趋势，但淀粉酶活性与其相反，呈先降后升的趋势；29日龄时，随饥饿时间的延长脂肪酶和淀粉酶活性均呈显著上升趋势。结果表明，饥饿会导致胭脂鱼仔鱼的生长、摄食和消化酶活性产生明显的变化，其补偿生长随饥饿时间的不同而不同；在恢复摄食后，不同饥饿程度仔鱼在不同恢复时间消化酶恢复策略并不一致，饥饿时间越长越倾向于对碳水化合物的利用，但其内在机制有待进一步研究。

To investigate the effects of different starvation periods on the growth capacity, feeding and activities of digestive enzyme of the Myxocyprinus asiaticus larvae under the condition of water temperature （19 ± 0. 5 ）℃, two experiments were performed. The first one was a controlled experiment with one complete starvation group（S） and one normal feeding group （C）. The second was the delayed first feeding experiment along with the initial feeding time groups ： 0 （ control group ）, 1,3,5,7,9 and 11 delayed days groups, denoted as D0, D1, D3, D5, D7, D9 and D11. The total experimental period lasted 29 days. Results showed that： （ 1 ） Since hatching,larvae＇ s first feeding was on the 7th day,and the yolk was exhausted on the 14th day, while PNR （ the point of no return） appeared on the 27th day, with conspicuous pectoral angle characteristics and significant increase in mortality around the PNR. （2）After refeeding, compared to the control group ,the D1 and D3 groups showed no significant difference in body weight,indicating a complete compensation effect. （3）During the l th to the 7th day starving process, the trypsin and amylase enzyme activity decreased significantly（P 〈 0.05） ,while when prolonging the starvation time to 9 and 11 days, the lipase and trypsin enzyme activity rose significantly （ P 〈 0.05 ）. After refeeding, with starvation time lasting, to the 19th day larvae,the trypsin activity significantly increased and then gradually decreased,but indicated the opposite trend on the amylase activity ,to the 29th day larvae, and both of lipase and amylase showed a significant upward trend. To sum up, our results indicated that starvation can cause significant changes of M. asiaticus in the larvae growth, feeding and digestive enzymes, along with different compensatory growth mechanism after various starvation time periods. After recovering feeding, the digestive enzymes recovery strategy is not consistent for larvae are with different starvation time. Totally, larvae are inclined to use the small carbohydrates along with starvation time lasting. But the inherent mechanism needs further study.