长薄鳅幼鱼消化道指数和消化酶活性研究

Studies on the digestive tube index and the activities of digestive enzymes in juvenile Leptobotia elongate

测定了长薄鳅(Leptobotia elongate Bleeker)幼鱼(8.0～110.1 g)的消化道指数和不同体重组(10 g、30 g、50 g)幼鱼的胃、肝胰脏、前肠、中肠、后肠的淀粉酶、胃蛋白酶、胰蛋白酶及脂肪酶活性。结果:(1)长薄鳅幼鱼肝指数平均为(1.400±0.004)%,比肠长平均为(0.418±0.080),体重与体长呈幂函数相关,相关式为:W=0.019L2.818 1(R2=0.948,P<0.01,n=43);鱼体肥满度在30 g组中最高。(2)各部位消化酶活性均以蛋白酶>脂肪酶>淀粉酶;各体重组淀粉酶活性在肝胰脏中最高(P<0.05);蛋白酶活性在胃和中肠中较高;脂肪酶活性沿消化道从前至后升高;(3)各部位淀粉酶活性在各体重组间变化不大,胃蛋白酶、肠段胰蛋白酶和脂肪酶活性随体重增加而下降。本研究认为长薄鳅幼鱼为杂食、偏肉食性,其消化酶活性存在组织特异性,体重30 g左右是其营养需求转变或者生长发育的重要时期。

Digestive tube index and digestive enzyme activities(amylase,trypsin,protease and lipase) in five tissues(stomach,hepatopancreas,foregut,midintestine and hindgut) of juvenile Leptobotia elongate were determined.The results showed that:(1) the hepatopancreas index is(1.4±0.004)%.The ratio of intestine length to body length was(0.418±0.080).The correlation relationship between weight and body length was a power function,and the correlation equation was W=0.019L2.818 1(R2=0.948,P<0.01,n=43).The 30 g group showed the highest fatness.(2) The protease /trypsin activities >lipase activities >amylase activities were found in five tissues of juvenile L.elongate.Hepatopancreas showed the highest amylase activities in all groups.The protease activities in stomach and midintestine were higher in present study,and lipase activities increased along the intestinal tract.(3) No significant difference in amylase activities in five tissues were found among body mass groups.Protease activities in stomach and trypsin activities in intestine decreased as the growth of fish.The result suggested an organic specificity of digestive enzymes and a heterophagous and partial carnivorous food habit of juvenile L.elongate,and an important period for nutritional requirement or growth and development was when fish grow up to about 30 g.