Study On The Maggot Culture As Substitute For Fishmeal In Diets Of Cultured Fish

Feeding trials were conducted to evaluate the effect of maggot culture as asubstitute for fish meal in practical diets for Monopterus albus, crucian carp, hybridtilapia(Oreochromis niloticus×O.aureus), and japanese seabass(Lateolabraxjaponicus) in indoor culture systerm(300L) or pond cages(2×2m). Studies were also toestimated appropriate percent of maggot culture in diets of cultured fish. Results ofthe present study are presented as follows:1. This study was conducted to estimate the effects of replacing fish meal (FM) in thediet of Monopterus albus (initial body weight25.35±0.51g) with maggot culture (MC)on growth, activities of digestive enzymes and some blood physiological-biochemicalindices. Five isonitrogenous and isoenergetic diets were formulated by replacing0%(control),12.5%,25%,37.5%and62.5%of the fishmeal protein with maggot culture,respectively. Each diet was randomly fed to triplicate groups of60fishes per cage(2×2m). Fish were fed once daily by hand at a rate of3%-5%of body weight duringten weeks. The results showed that fish fed diets supplemented maggot cultureshowed significantly higher survival rate than the control diet (P<0.05). The weightgain rate (WGR) was first significantly increased and then leveled off. Fish fed thediet with25%maggot culture showed significantly higher growth than the controlgroup (P<0.05). The activities of protease, lipase in intestine were significantlyincreased with increasing dietary maggot culture levels (P<0.05), however, theactivities of amylase were not significantly affected by dietary levels of maggotculture. Serum total protein (TP), triglyceride (TG), serum glucose were notsignificantly affected by dietary levels of maggot culture, but the serum totalcholesterol (TC) was significantly decreased with increasing dietary levels of maggotcunlture (P<0.05). Activity of lysozyme increased with increasing dietary maggotculture level and no significant differences were observed in the activity of superoxidedismutase among dietary treatments. Activities of glutamic-oxaloacetic transaminase(GPT) in serum decreased and glutamic-pyruvic transaminase (GOT) in serum was significantly decreased with increasing dietary maggot culture levels (P<0.05). Nosignificant differences in body moisture, protein, lipid and ash contents were observedamong dietary treatments. These results showed that, the maggot culture was a newtype and useful protein resource which can replaced62.5%fishmeal protein in the diefor Monopterus albus.2. This study evaluated the effects of replacing fish meal (FM) in the diet of cruciancarp (initial body weight12.01±0.09g) with maggot culture (MC) on growth, activityof digestive enzymes and some blood physiological-biochemical indices. Fiveisonitrogenous and isoenergetic diets were formulated by replacing0%(control, D1),20%(D2),33.3%(D3),66.7%(D4) and100%(D5) with maggot culture,respectively. Each diet was randomly fed to triplicate groups of25fishes per tank(300L). Fish were fed to satiation twice daily (08:00and16:00) for ten weeks. Theresults showed that survival ranged from97%to100%and did not significanlty(P>0.05) differ. there were no significantly difference (P>0.05) in growthperformance among fish fed the diets1-5. and the weight gain was first significantlyincreased and then increased with maggot culture levels. The activities of protease,lipase and amylase of the fish were not significantly (P>0.05) affected by dietarytreatments. No significantly differences (P>0.05) in serum total protein (TP),triglyceride (TG), glucose and total cholesterol (TC) were found among fish fed diets1-5. Catalase, superoxide dismutase activity、C3and C4were not affected by dietarylevels of maggot culture (P>0.05). These results showed that, the maggot culture wasa newly and useful protein resourse which can completely replaced fishmeal, and thebest replacemental fishmeal protein was66.7%in the die for crucian carp.3. This study evaluated the effects of replacing fishmeal (FM) in the diet of hybridtilapia (Oreochromis niloticus×O.aureus)(initial body weight12.01±0.09g) withmaggot culture (MC) on growth and immunity. Five isonitrogenous and isoenergeticdiets were formulated by replacing0%(control, D1),20%(D2),40%(D3),80%(D4)and100%(D5) with maggot culture, respectively. Each diet was randomly fed totriplicate groups of30fishes per tank (300L). Fish were fed to satiation twice daily(08:00and16:00) for eight weeks. The results showed that survival ranged from90%to100%and did not significanlty (P>0.05) differ. There were no significant difference(P>0.05) in growth performance among fish fed the diets1-5. And the weight gainwas first increased and then increased with maggot culture levels. Catalase, Superoxide dismutase activity and serum total protein (TP) were not affected bydietary levels of maggot culture (P>0.05). No significantly differences (P>0.05) incondition factor, hepatosomatic index and viscera ratio were found among fish feddiets1-5. There were no significantly differences in moisture, protein, lipid and ashcontent of whole body and musle among dietary treatments. Apparent digestibilitycoefficients of dry matter and protein were72.45%and92.17%respectively. Thesegrowth results showed that, the maggot culture was a newly and useful proteinresourse which can completely replaced fishmeal, and the best replacemental fishmealpercent was40%in the die for hybrid tilapia(Oreochromis niloticus×O.aureus).4. This study evaluated the effects of replacing fish meal (FM) in the diet of japaneseseabass (Lateolabrax japonicus)(initial body weight10.70±0.03g) with maggotculture(MC) on growth, activity of digestive enzymes and some bloodphysiological-biochemical indices. Six isonitrogenous and isoenergetic diets wereformulated by replacing0%(control, D1),15%(D2),30%(D3),45%(D4),75%(D5)and100%(D6) with maggot culture, respectively. Each diet was randomly fed tofourfold groups of25fishes per tank (300L). Fish were fed to satiation twice daily(09:00and16:30) for six weeks. The results showed that the survival and growth weresignificantly affeceted by dietary levels of maggot culture(P<0.05). fish fed the dietD5and D6showed the lower survival rate and weight gain rate than controldiet(P<0.05) and no significantly difference were found between the other diet withcontrol diet. There were no significant difference in condition factor, hepatosomaticindex and viscerasomatic index among fish fed the diet1-6. The activity of protease inintestine was decreased with increasing maggot culture levels. However, the activityof lipase and amylase keep stable. The activites of glutamic-oxaloacetictransaminase(GPT), glutamic-pyruvic transaminase (GOT) and alkaline phosphatase(ALP) in serum were not affected by dietary levels of maggot culture. Serum totalprotein (TP) and albumin was first significantly increased and then level off withmaggot culture levels, fish fed the diet with100%maggot culture showed the lowestvalues. The content of triglyceride (TG), total cholesterol (TC) and glucose in serumwere gradually decreased with increasing dietary mggot culture levels. There were nosignificantly difference (P>0.05) in serum globin and urea nitrogen among fish fed thediets1-6. Fish fed the diets with75%and100%protein from maggot culture hadsignificantly lower fish protein and higher ash content than control group (P<0.05).No significantly differences (P>0.05) were found in whole body moisture and lipid. Results of the present study indicated that protein from maggot culture couldsubstitute less than30%for fish meal protein without influencing the growth ofjapanese seabass.