牙鲆幼鱼消化能力与肠道蛋白酶活性的研究

对体重7.5~20.0 g的牙鲆幼鱼的摄食比率、食物的消化时间、消化道不同部位蛋白酶的最适pH值、蛋白酶和脂肪酶的分布和摄食后不同时间蛋白酶的变化规律进行了研究。结果表明:牙鲆幼鱼的平均摄食量为净体重的5.89%。摄食配合饲料后约5 h,胃内的食物基本排空。pH值为2.6~3.0时胃蛋白酶的活性最高,pH值为8.2时幽门盲囊和肠道的蛋白酶活性最高。消化道中蛋白酶活性的变化趋势为由前向后逐渐降低,以胃蛋白酶活性最高;脂肪酶活性变化趋势为由前向后逐渐增高,以肠道脂肪酶活性最高。摄食后不同时间牙鲆消化道各部位的蛋白酶活性有显著变化,胃蛋白酶活性在摄食后3 h达到最高值,摄食后7 h降至极低水平;肠道蛋白酶活性在摄食后呈现逐渐增高趋势;幽门盲囊中蛋白酶活性变化与胃和肠道密切相关。在下一次摄食前消化道各部位蛋白酶活性均处于较高水平。

Digestive Ability of Juvenile Japanese flounder Paralichthys olivaceus

The feeding coefficient,digestive period of food,optimal pH value of protease in different parts of a digestive tract,activities of protease and lipase as well as protease varieties at different times after feeding were studied in juvenile Japanese flounder Paralichthys olivaceus.The results indicated that the feeding coefficient was(5.89%,) and that the food was egested from the stomach 5 hours after feeding.The optimal pH value was 2.6~(3.0) in the stomach and 8.2 in the intestine and diverticulum pyloricum.The protease had high activity in the stomach,and gradually decreased from the diverticulum pyloricum to intestine.The lipase,however,had high activity in the intestine,and gradually increased from diverticulum pyloricum to intestine.The activities of protease changed significantly after feeding.Activity of protease in stomach reached the maximal value 3 hours after feeding and decreased to extremely low value at postprandial 7 hours.Activity of protease increased gradually in the intestine after feeding,and was closely related to the other two tissues in the diverticulum pyloricum.The activity of protease was relatively high in all the three tissues just 3 hours before feeding.