The Study On Utilization Of Silkworm Pupae In Diet For Jian Carp (Cyprinus Carpio Var. Jian)

It is well known that most of the high dietary protein requirement in fish would bebetter being supplied by fishmeal (FM) because of its nutritional value and palatability.However, with the rapid development of aquaculture industry, the long-term sustainabilityof fish farming might be threatened by its present overdependence on FM due to theemerging tendency of the shortage of FM production. Therefore, partial or total replacementof FM in aquatic feed with animal or plant protein-rich ingredients has become a focus.Silkworm pupae meal (SP) is a reasonable candidate for its superior nutrition value andabundant resources in china. However, the restrictive factors of SP can not be ignored,especially the27%lipids rich in unsaturated fatty acid which is easy to result in oxidativerancidity. Thus the substitution level appears to be limited. This study was going to makeefforts on the follow topics:(1) Effect of replacement of dietary fish meal with silkwormpupae meal on growth performance, body composition, intestinal protease activity andhealth status in juvenile Jian carp (Cyprinus carpio var. Jian);(2) Effect of replacement ofdietary fish meal with defatted silkworm pupae on growth performance, body compositionand health status in Juvenile Cyprinus carpio var. Jian. The aim of the study was to identifythe optimum substitution level of FM with SP or DSP in Cyprinus carpio var. Jian diets,clarify the defat necessity for SP and feasibility for crystalline L-lysine supplementation inDSP-base diets. Then offering theory basis and reference data for silkworm pupaeutilizations in Cyprinus carpio var. Jian diets.(1) This study investigated the effect of replacement of graded dietary fish meal (FM)protein (0,50%,60%,70%, and80%) with silkworm pupae meal (SP) on growthperformance, body composition, intestinal protease activity, and health status in juvenileJian carp. Triplicate groups comprising18fish (15.96±0.66g) were fed one of fiveisonitrogenous and isocaloric diets (designated SP0, SP50, SP60, SP70, or SP80) for8weeks. The experiment results showed as follow: The final body weight (FBW), specificgrowth rate (SGR) and condition factor (CF) of fish in the SP60, SP70and SP80groupswere significantly lower than those for fish in the SP0group (P<0.05). Feed intake (FI)decreased while increasing SP and, the optimal protein efficiency appeared in the SP50.There was no significant difference in the muscle amino acid of the SP-based diet groups, and total amino acids generally declined. A significant increase of relative gut length wasobserved in SP70and SP80groups (P<0.05). Muscle protein content in SP50groupsignificant higher than SP80group (P<0.05). Muscle lipid content was inversely correlatedwith muscle protein content. Muscle ash content decreased with increasing SP in the diets.Among all serum biological indices, only ALT of SP80group was observed to besignificantly higher than other groups (P<0.05). Hepatic SOD activity decreased and MDAcontent increased with increasing FM replacement levels, but only SP80group wassignificant higher in SOD activity, and lower in MDA content than the other groups(P<0.05). The gene expressions of Heat shock protein70were up-regulated with increasingdietary SP level up to70%and that of SP70group was significantly higher than SP0group(P<0.05), but it greatly decreased in SP80group and significantly lower than SP70group(P<0.05). Intestinal protease activity increased at first, then going back down withincreasing SP levels. Intestinal microvillis of SP0and SP50groups showed more regularshapes, while shorter length of them appeared in SP70and SP80groups. Hepatocytes inSP0, SP50and SP60groups showed a polygonal shape with centrally located nuclei andclear cell boundaries, but it was difficult to distinguish the cell boundaries easily in SP70,and SP80groups especially. The study demonstrated that it is possible to replace50%dietary FM protein with SP without compromising its growth, while the supplement levelup to60%would result adverse influence on growth performance and health status of Jiancarp.(2) This study investigated the effect of replacement of graded dietary FM protein (0,25%,50%, and75%) with defatted silkworm pupae meal (DSP) in juvenile Jian carp, andalso the effect of crystal L-lysine supplementation in the later75%substitution group.Triplicate groups comprising18fish per tank (15.30±2.97g) were fed one of fiveisonitrogenous and isocaloric diets (described as DSP0, DSP25, DSP50, DSP75, orDSP75-Lys) for56days. The FBW, WGR, SGR, FCR and protein efficiency ratio (PER) offish in the DSP-based diets groups were decreased with the relative gut length (RGL) risinggradually. The FBW and WGR in DSP75group were significantly lower than those inDSP0group (P<0.05). No significant difference of fed intake and hepatosomatic index werefound among the treatments (P>0.05), as well as the whole body crude protein and moisture,and muscle amino acids composition (P>0.05), but the crude lipid content in DSP75groupwas significantly higher than that in DSP0group (P<0.05). Moreover, serum ALT activityincreased along with the increased DSP levels among all the DSP-based groups and that ofDSP75group was markedly higher than that in the DSP0, DSP25and DSP50groups(P<0.05). The serum LDL-c and GLU contents were decreased with increased DSP levels. The GLU content in DSP75and DSP50group was significantly lower than that in DSP0group (P<0.05). With increased FM protein replacement levels, the hepatic total superoxidedismutase (T-SOD) activity decreased among the groups, with the significantly lowerT-SOD activity appeared in DSP75group (P<0.05). With additional crystal L-lysinesupplementation, the indicators mentioned above were improved to a certain degree exceptthe transaminase activities and antioxidant index. It is concluded that it is feasible tosubstitute50%FM protein with DSP in Jian carp diet and the crystal lysine supplementationcould improve the body protein accumulation status.Conclusion: Considering the growth index, body composition, protease activity andhealth status indicators, this study demonstrates that:(1) It is possible to replace50%of thedietary FM protein with SP without affecting growth, but supplementing with60%or morewill adversely affect growth performance and the health status of Jian carp.(2) It is feasibleto substitute50%FM protein with DSP in Jian carp diet and, the substitute level could beimproved to a certain extent by the crystal lysine supplementation.(3) Degreasing methodfor SP can not improve the substitute level for FM in Jian carp juvenile’s diet.