Study On The Application Of Black Soldier Fly(Hermetia Illucens) Larvae Meal In The Diet For Juvenile Largemouth Bass(Micropterus Salmoides)

An 62-day experiment was conducted to study the effect of black soldier fly larvae(Hermetia illucens)powder on apparent digestibility,growth,digestive enzyme activity,hematology indices and immune function in Largemouth bass(Micropterus salmoides).The whole experiment is divided into two parts:digestibility experiment and growth experiment.Of which,five experimental diets were prepared to replace 0(T0),7.5%(T1),15%(T2),22.5%(T3),and 30%(T4)fish meal with black soldier fly larvae(Hermetia illucens)powder,525 juvenile largemouth bass(Micropterus salmoides)with an average body weight of(4.89±0.10)g were selected and randomly divided into divided into 5 groups with 3 replicates per group and 35 tails per repeat.The experiment was carried out in a circular fibre drum(diameter 90 cm,height 80 cm,water volume 300L).The results are as follows:1.Determination of apparent digestibility of black soldier fly larvae(Hermetia illucens)powder.The apparent digestibility of juvenile largemouth bass(Micropterus salmoides)to the dry matter,crude protein,Crude lipid,calcium and phosphorus of black soldier fly larvae(Hermetia illucens)were 71.22%,88.14%,87.50%,32.46% and 67.40%respectively.Largemouth bass(Micropterus salmoides)juveniles can digest and utilize black soldier fly larvae(Hermetia illucens)powder,which can be used as protein raw material for largemouth bass(Micropterus salmoides)juveniles.2.The effect of black soldier fly larvae meal(Hermetia illucens)replacing fish meal on growth performance,body composition and digestive enzyme activity of juvenile largemouth bass(Micropterus salmoides).As the substitution level of black soldier fly larvae meal(Hermetia illucens)increases,weight gain rate and specific growth rate of juvenile largemouth bass(Micropterus salmoides)showed an upward trend and then a downward trend,hepatosomatic index and viscerosomatic index showed a decreasing trend,when it reached 22.5%,the growth of juvenile largemouth bass(Micropterus salmoides)was the highest,hepatosomatic index and viscerosomatic indexwere the lowest.There was no significant change in mositure,crude protein,crude lipid,intestinal lipase and amylase(P>0.05),but intestinal and liver proteases in T3 group were the highest.3.The effect of black soldier fly larvae meal(Hermetia illucens)replacing fish meal on serum biochemical indexes and serum immune antioxidant indexes of juvenile largemouth bass(Micropterus salmoides).There was no significant change in Serum glucose(GLU),triglyceride(TG),alanine aminotransferase(ALT),aspartate aminotransferase(AST),lowdensity lipoprotein(LDL)and urea nitrogen(UN)in juvenile largemouth bass(Micropterus salmoides)(P>0.05).As the substitution level of black soldier fly larvae meal(Hermetia illucens)increases,serum albumin(ALB),globulin(GLOB),total protein(TP),malondialdehyde(MDA)and alkaline phosphatase(AKP)all showed a trend of rising first and then falling,among them,globulin(GLOB),total protein(TP)in T3 group had significant increase than control group,malondialdehyde(MDA)and alkaline phosphatase(AKP)in T4 group had significant decrease than control group.At the same time,high-density lipoprotein ratio to low-density lipoprotein(H/L),the glutathione peroxidase(GSH-Px),complement C3 and the activity of alkaline phosphatase all showed an increasing trend,among them,the H/L in T3 and T4 groups were significantly higher than control group(P<0.05),the activity of ACP in T2,T3,T4 groups were significantly higher than that of the control group(P<0.05),while the glutathione peroxidase(GSH-Px)and complement C3 of each test group were significantly higher than that of control group(P<0.05).Based on the above research results,it can be concluded that juvenile largemouth bass(Micropterus salmoides)can digest and use black soldier fly larvae(Hermetia illucens)powder.Replacing the appropriate proportion of fishmeal with black soldier fly larvae(Hermetia illucens)powder can promote the growth of largemouth bass larvae(Micropterus salmoides),but it is too high.Proportion will negatively affect the growth and physiological health of fish.Under the conditions of this experiment,it is appropriate to replace 22.5% fish meal with Black soldier fly larvae meal(Hermetia illucens)in the feed of juvenile largemouth bass(Micropterus salmoides).