卵形鲳鲹消化酶活力的研究Ⅵ 饥饿对幼鱼存活和消化酶活力的影响

研究了饥饿对卵形鲳鲹(Trachinotus ovatus)消化器官中主要消化酶(蛋白酶、淀粉酶、脂肪酶)活力的影响。在水温25±0.5℃、盐度20±1条件下,对卵形鲳鲹幼鱼进行短期饥饿处理(0 d、3 d、6 d、9 d、12 d),并分别测定卵形鲳鲹幼鱼的比内脏重与蛋白酶、淀粉酶和脂肪酶3种消化酶的活力。结果表明,随着饥饿时间的延长,卵形鲳鲹幼鱼的比内脏重不断下降,饥饿第0～6天下降速度最快(P﹤0.01),6 d后下降不显著(P﹥0.05);蛋白酶活力表现为饥饿第0～6天不断上升,第9天下降,第12天又显著升高(P﹤0.01),并且饥饿后的蛋白酶活力始终高于对照组(P﹤0.01);淀粉酶活力不断下降,并在第3天下降最显著(P﹤0.01);脂肪酶活力在饥饿前9 d总体上下降,第12天活力明显上升并高于对照组(P﹤0.01)。饥饿第8天开始出现幼鱼死亡,至第12天幼鱼的存活率为64.67%,表明第8天是卵形鲳鲹幼鱼饥饿致死的临界期。

Digestive enzyme activity of Trachinotus ovatus Ⅵ Effects of starvation on survival and enzyme activity in young fish

Trachinotus ovatus was starved for 12 days when the water temperature was 25±0.5 ℃and the salinity was 20±1,and the activity of protease,amylase and lipase in its digestive organs and the ratio of viscera weight to body weight were measured on the 0,3rd,6th,9th,and 12th day of starvation,respectively.The results showed that starvation had definite effects on the activity of all test enzymes and the ratio of viscera weight to body weight.The ratio of viscera weight to body weight and the amylase activity were found to decrease gradually as the starvation period increased;the ratio of viscera weight to body weight had the fastest decline from the 0 to 6th day after starvation(P﹤0.01),and did not decrease significantly after 6 days(P﹥0.05).The amylase activity decreased throughout the experiment,and was significantly lower 3 days after starvation(P﹤0.01).With the prolongation of starvation,the protease activity was found to increase gradually,and was higher than that of the control(P﹤0.01).In general,the lipase activity decreased from the 0 day to 9th day,and increased significantly on the 12th day of the starvation(P﹤0.01).Mortality was observed on the 8th day of the starvation,and the survival rate was 64.67% on the 12th day after starvation,indicating that the threshold time of death by starvation laid on the 8th day after starvation.