苦草粉对草鱼幼鱼生长性能与生理生化性能的影响

Effects of Adding Vallisneria natans Meal to Diet on Growth Performance,Physiological and Biochemical Properties of Juvenile Grass Carps(Ctenopharyngodon idellus)

本研究评价了苦草(Vallisneria natans)粉在草鱼(Ctenopharyngodon idellus)饲料中的应用效果。以不含苦草粉的基础饲料(VN0组)为对照,分别用10%(VN1组)、20%(VN2组)和30%(VN3组)的苦草粉替代基础组饲料中的次粉和米糠,配制出4种实验饲料,另设置1组只投喂新鲜苦草的青饲料组(VN组)。选用初始体重为(18.85±0.20)g的草鱼幼鱼在室内水泥池网箱进行为期56 d的养殖实验。结果显示,添加苦草粉不影响草鱼的生长性能、存活率和饲料系数。随着苦草粉添加量的增加,内脏指数及肝胰脏指数显著降低;前肠淀粉酶活力显著增强,中、后肠淀粉酶活力显著降低;对照组前、中、后肠蛋白酶活力依次增强,随着苦草粉含量的增加,前肠蛋白酶活力显著增强,中肠蛋白酶活力表现出先增强再减弱再增强的变化,VN1组显著高于其他组,后肠蛋白酶活力呈现显著降低的趋势;肝胰脏SOD活力显著提高,MDA含量先下降后上升,VN3组最高。血清总蛋白含量有上升的趋势,VN3组显著高于其他组;血清白蛋白含量呈现先增加后降低的趋势,VN1组最高;血清ALT活力先增强后减弱;与对照组相比血清AST活力显著降低,各苦草粉组之间没有显著性差异。添加苦草粉显著降低了饲料表观消化率,但在一定程度上增强了草鱼对嗜水气单胞菌的抗感染能力。VN组出现负增长现象,内脏指数及肝胰脏指数、血清白蛋白、球蛋白及ALT都显著低于其他组;肠道各段淀粉酶活力显著高于各实用饲料组;中肠蛋白酶活力显著高于对照组,后肠蛋白酶活力显著低于对照组。研究表明,饲料中添加10%~30%苦草粉对草鱼生长没有影响,且有利于鱼体健康,可以作为草鱼饲料原料进行资源化的利用;苦草粉的使用效果明显优于新鲜苦草。

In this study,the effect of Vallisneria natans meal used as feed ingredient in the diet of grass carp(Ctenopharyngodon idellus)on growth,physiological,and biochemical properties was evaluated.Four isonitrogenous and isoenergic diets were formulated by replacing the secondary powder and rice bran with 0(VN0,control),10%(VN1),20%(VN2),and 30%(VN3)V.natans meal.In addition,a group that was fed only with fresh V.natans was designed.Juvenile grass carp of initial weight(18.85±0.20)g were selected to be cultured for 56 days in indoor cement tank cages.The results showed that addition of V.natans meal did not affect the growth performance,survival rate of grass carp,and feed coefficient.With the increase in the amount of V.natans meal,the visceral index and hepatopancreas index significantly decreased,the activity of amylase in the foregut was significantly increased,and that in the middle and rear intestines was significantly decreased.In the control group,the protease activity of foregut,and middle and rear intestines,in turn,strengthened,and with the increase in the content of V.natans meal the activity of foregut protease was significantly increased;meanwhile,midgut proteinase activity increased first,then decreased,and increased again.The highest value was observed in group VN1,and protease activity in the posterior intestine showed a significant decrease trend.The superoxide dismutase(SOD)activity of the hepatopancreas was significantly increased,whereas malondialdehyde(MDA)content decreased first and then increased,and that in group VN3 was the highest.The content of serum total protein increased significantly,whereas the serum albumin content increased first and then decreased,and the highest value was found in group VN1.Compared with the control group,serum alanine aminotransferase(ALT)activity increased and then recovered to the control level,and serum aspartate aminotrasferase(AST)activity significantly decreased in V.natans meal groups,and there was no significant difference among the V.natans meal groups.The addition of V.natans meal resulted in significantly reduced apparent digestibility of the diets and enhanced resistance ability of grass carp to Aeromonas hydrophila to some extent.Group VN showed negative growth and depressed visceral index,hepatopancreas index,serum albumin,globulin,and ALT.The activity of amylase in the intestinal segments was significantly higher than that in all practical formulated diets.The activity of midgut protease in VN group was significantly higher than that in the control group,and that of hindgut protease was significantly lower than that of the control group.The above results showed that the addition of 10%~30% V.natans meal in the diet had no effect on the growth of grass carp,but was beneficial to the health of the fish body.The results indicated that V.natans meal used as the raw material of grass carp feed for resource utilization would be much better than fresh V.natans.