饲料蛋白水平对拉萨裸裂尻幼鱼肠道和肝脏的消化酶活性及组织结构的影响

Effect of dietary protein level on digestive enzyme activity and histological structure in intestine and liver of juvenile Schizopygopsis younghusbandi

为探究饲料蛋白水平对拉萨裸裂尻(Schizopygopsis younghusbandi)幼鱼肠道和肝脏的消化酶活性及组织结构的影响,设计出蛋白质水平分别为20%、25%、30%、35%、40%、45%的6种等脂等能的饲料,饲喂初始体质量为(22.42±0.56)g的拉萨裸裂尻幼鱼60 d。结果显示,随着饲料蛋白水平升高,肠道和肝脏的蛋白酶活性呈先升高后降低的趋势,其中35%蛋白水平组蛋白酶活性显著高于其他实验组(P<0.05)。脂肪酶和淀粉酶活性随着饲料蛋白水平的升高呈降低趋势(P<0.05)。前、中、后肠的管壁厚度和绒毛高度呈先升高后降低的趋势(P<0.05),其中在30%蛋白水平组的前肠和中肠管壁厚度最高,35%蛋白水平组后肠管壁厚度最高,30%蛋白水平组前肠、中肠和后肠绒毛高度最高。饲料蛋白水平高于35%时会损伤肝脏组织结构。在该实验条件下,综合考虑鱼体肠道和肝脏中消化酶活性及组织结构,拉萨裸裂尻幼鱼饲料蛋白水平以30%为宜。

To explore the effects of different feed protein levels on the digestive enzyme activity and histological structure in the intestine and liver of juvenile Schizopygopsis younghusbandi,we designed six kinds of equal-energy experimental feeds with different protein levels(20%,25%,30%,35%,40%,45%)to feed the juveniles with initial body mass of(22.42±0.56)g for 60 d.The results show that with the increase of feed protein level,the protease activity in intestine and liver increased first then declined.The protease activity in 35%protein group was significantly higher than that in the other groups(P<0.05).The lipase and amylase activities reduced significantly(P<0.05).The wall thickness and villus height of foregut,midgut and hindgut all increased and then decreased(P<0.05).The wall thickness of foregut and midgut were highest in 30%group,while the wall thickness of the hindgut was highest in the 35%group.The villus height of foregut,midgut and hindgut were highest in 30%group.Feed protein level higher than 35%may damage liver tissue structure.Under this condition,considering the digestive enzymes activity and histological structure of intestines and liver,the optimum protein level of juvenile S.younghusbandi should be 30%.