Effects Of Microcapsule Feed On Growth,Digestion,Nonspecific Immunity In Larvae Of Lager Yellow Croaker

Microencapsulated diet,boasts its nutrition,palatability and stability,and has been recognized an ideal aquatic breeding feed.In this experiment,we formulated microencapsulated diet as breeding feed of Larimichthyss crocea larvae,and breed 10 days old Larimichthyss crocea larvae with feed mixed with live prey and different percentage of microencapsulated diet,respectively,0%(control group),25%,50%,75%,for 15 days and 32days,and measure the body length and weight at 25 days old and 42 days old.Through the comparison of physical and chemical prosperities of microencapsulated diet,growth and development index of Larimichthyss crocea,total protein concentration,digestive enzyme in tissue,and non-special immunity index,study the influence of different feed formula on microencapsulated diet larvae.The results of this experiment were presented as follows:1.Microencapsulated diet has appropriate particle size(Feed one is 27.77±11.83?m,feed two is 35.26±11.64?m),preferable suspension(Feed one is 33.80±1.08%,feed two is 20.67±0.26%),lower dissolution rate(Feed one is 3.20±0.32%,feed two is 8.30±0.46%),balanced nutrition and good stability in water due to the external envelope.2.The influence of microencapsulated diet on growth condition of Larimichthyss crocea larvae.With the increasing percentage of microencapsulated diet,the body length and weight of Larimichthyss crocea larvae decrease.100%live prey group has biggest body length and weight,they are 20.88±1.40mm and 60.96±5.80mg.But the differences between 25%microencapsulated diet and 75%live prey and 100%microencapsulated diet is slight,which means,on certain extent,microencapsulated diet could partially replace live prey.The specific growth rate of body length decreases with the growth of larvae,and the specific growth rate of weight shows a downward in the period of 10-25 days old,and shows a upward in the period of 25-42 days old.100%live prey group has highest survival rate,it is 20.54%.3.The influence of Microencapsulated diet on the total protein concentration of Larimichthyss crocea larvae.This experiment uses test box which produced by NanJingJianCheng Bioengineering Institute,and determines the absorbance to confirm the total protein concentration of Larimichthyss crocea larvae by BCA method.With increase of the percentage of microencapsulated diet,the total protein concentration decreases.4.The influence of microencapsulated diet on digestive index of Larimichthyss crocea.This experiment uses test box produced by NanJingJianCheng Bioengineering Institute,determines the absorbance to confirm the amylase activity of Larimichthyss crocea larvae by iodine-starch colorimetry,determines the absorbance to confirm the lipase activity of Larimichthyss crocea larvae by 50T/48 method,and determines the absorbance to confirm the pepsin and trypsin activity of Larimichthyss crocea larvae by kit method.The amylase activity in Larimichthyss crocea tissue of experimental group is averagely higher than control group.Except for tailpart group of 25 days old,lipase activity in Larimichthyss crocea tissue is higher than control group.In tailpart group of 25 days old,the lipase activity gradually decreases with the increase of microencapsulated diet percentage.Except for tailpart group of 42 days old,pepsin activity in Larimichthyss crocea tissue is higher than control group.In tailpart group of 42 days old,the pepsin activity gradually decreases with the increase of microencapsulated diet percentage.Except for tailpart group of 25 days old,trypsin activity in Larimichthyss crocea tissue is higher than control group and shows upward tendency.In forepart group of 25 days old,D75 group has biggest pepsin activity,it is 6.65±0.09U/mgprot and different obviously with other group(P<0.01).5.The influence of microencapsulated diet on the nonspecific immunity index of Larimichthyss crocea·This experiment uses test box produced by NanJingJianCheng Bioengineering Institute,determines the absorbance to confirm the total super oxide dismutase activity of Larimichthyss crocea larvae by xanthine oxidase method(hydroxylamine method),determines the absorbance to confirm the lysozyme activity of Larimichthyss crocea larvae by blank control method,and determines the absorbance to confirm the alkaline phosphatase activity of Larimichthyss crocea larvae by 50T/48 sample method.Except for the forepart group of 42 days old,the total superoxide dismutase activity of Larimichthyss crocea larvae is higher than experimental group,and in the forepart group of 42 days old,group with 50%Microencapsulated diet and 50%live prey has highest T-SOD activity,is 44.19±0.45U/mgprot.The calculation of lysozyme(LMZ)are all negatives,possibly due to larvaes are not mature enough without lysozyme.As for phosphatase activity,the forepart group of 25 days old and 42 days old are in downwards and the tailpart groups are in upwards;the phosphatase activity of 25 days old is higher than 42 days old,which demonstrates that 25 days old Larimichthyss crocea larvae has comparative higher immunity.