Quality Evaluation Of Crabseed From Different Sourced Eriocheir Sinensis

Culture performance and disease resistance are important index to evaluate the larval quality of fishery animals.Previous research has shown that wild and selected juvenile Chinese mitten crab possess certain advantages during adult culture stage,and formulated diets are superior for crab seed quality compared to traditional diets.The difference of early culture performance and disease resistance between juvenile crabs from different sources has been remained unclear,this is quite negative for the germplasm resources evaluation of wild juveniles and the exploration of superior germplasm.Therefore,it is necessary to compare the culture performance,disease resistance and non-specific immunity of juvenile Chinese mitten crab from different resources,and thus provide fundamental date for the exploration of superior germplasm and selective breeding.Exp.1 Comparison of early culture performance,disease resistance and non-specific immunity in wild-caught and pond-reared juvenile Chinese mitten crab Eriocheir sinensisAlthough wild-caught juvenile Eriocheir sinensis(WC)has the better culture performance compared to pond-reared juvenile crabs(PR),the difference of disease resistance,immunity and early culture performance between wild-caught and pond-reared juveniles has been remained unclear.Based on the culture experiment,pathogen challenge test and the analysis of non-specific immune index,this study was conducted to compare the early culture performance(include the first molt interval,survival rate and weight gain rate),the mortality during the pathogen challenge test and immune indices between WC and PR populations.The results showed that:(1)the first molt interval and weight gain rate(WGR)of either male or female WCs were significant lower to those of PRs,however there was no significant difference in survival rate and special growth rate(SGR)between the two groups(P>0.05);(2)The cumulative mortality of WC during the pathogen challenge test within 12–96 h was lower than that of PR population,and the cumulative mortality of WC was only 28.3% post 96 h of pathogen challenge test,which was overtly lower than that of PR(50.0%);(3)In terms of the non-specific immune indices in hepatopancreas,WC had significantly lower ALP activity compared to the PR for both males and females,Males of WC had the significantly higher T-AOC and NO,than the males of PR while females of WC had the lower MDA than female PRs;(4)In terms of the non-specific immune indexes in hemolymph,WC had the significantly higher NO but the lower ACP than the PR in both males and females;moreover,female WCs had the higher T-AOC,Hc and GR levels,but the lower ALP,?-GT and GSH-Px than the female PRs.In conclusion,the pond-reared juveniles had the better culture performance during the early culture stage,while wild-caught juveniles had the better immune ability and the lower mortality than the pond-reared juveniles.Therefore,the two types of crabseeds have their own advantages,and the inherent mechanism causing the difference in those parameters remain to be further studied.Exp.2 The comparison of immune performance of juvenile crabseeds among the second year early-maturing,late-maturing and non-selective populations of Chinese Mitten Crab Eriocheir sinensisThe previous studies have shown selective breeding is effective methods to change the mature time for the animals.Since 2011,the early-maturing(EM)and late-maturing(LM)strains of second year E.sinensis have been established and reproduced to the third generation,little is known for the effects of selective breeding on the crabseed quality of juvenile E.sinensis.The immune performance is an important criteria for the evaluation of crabseed quality.Therefore,this study was aimed to evaluate the survival during pathogen challenge test and immune indices of juvenile crabs among EM,LM and non-selective populations(as the control)based on the methods of pathogen challenge test and the analysis of non-specific immune indices.The results showed that:(1)The cumulative mortality of the control was lower than EM and LM populations for both males and females during pathogen challenge test;there were the certain gender differences between males and females,while the lowest mortality was found on the males of LM and females of EM,respectively.(2)In terms of the non-specific immune indicies of the hepatopancreas,EM had higher activities of ALP and EM also had higher activities of ACP than than LM for both males and females(P < 0.05).In addition,the male EM and LM had the significantly higher T-AOC and POD than the control,and the MDA and GSH-Px of female EM were notable higher than that of the females from the other two populations;(3)In terms of the non-specific immune indexes in hemolymph,despite of males or females,EM had higher ACP activities than the control while LM had the lowest GR activities among three populations.Furthermore,female EM had the significantly higher activities of ?-GT and T-AOC than female LM.In conclusion,the crabseeds from early-maturing(EM)and late-maturing(LM)strains has the better disease resistance and immunity than non-selective populations,and the EM had the slightly better performance on indices of antioxidation and immunity than the LM.Exp.3 Effects of three feeding modes on the early culture performance,non-specific immunity and disease resistance of juvenile chinese mitten crabFormulated diets,traditional diets and their mixture feeding are three common feeding modes for the culture of juvenile Chinese Mitten Crab(Eriocheir sinensis),but it is unclear for the crabseed quality produced by these three feeding modes.Therefore,this study was conducted to compare and evaluate the effects of three feeding modes on the early culture performance,immunity and the mortality during the pathogen challenge test for the juvenile crabs produced by different feeding modes based on the culture experiment,the analysis of non-specific immune index and pathogen challenge test.The poison test use the strain of Aeromnas hvdrophilia Y-2-L-1 which virulence is strong.The results showed that:(1)Despite of males or females,formulated diets treatment(FD)had the shorter period to the first molting than traditional diets treatment(TD)and mixture diets treatment(MD),and the significant higher weight gain rate(WGR)and specific growth rate(SGR)was found on formulated diet;(2)In terms of the non-specific immune indicies in the hepatopancreas,although formulated diets treatment(FD)had the higher activity of ?-glutamyl transferase(?-GT),total antioxidant capacity(T-AOC)and superoxyde dismutase(SOD)than traditional diets treatment(TD)and mixture diets treatment(MD),the only significant difference was found on ?-glutamyl transferase(?-GT);however the traditional diets treatment(TD)had the higher acid phosphatase(ACP),malondialdehyde(MDA),nitric oxide(NO)and peroxidase(POD)activities than the other two treatments,while the significant differences were found on acid phosphatase(ACP)and nitric oxide(NO)for both males and females;(3)In terms of the non-specific immune indexes in hemolymph,formulated diets treatment(FD)had the higher glutathione peroxidase(GSH-Px)and total antioxidant capacity(T-AOC)activities than the traditional diets treatment(TD)and mixture diets treatment(MD)while traditional diets treatment(TD)had the higher alkaline phosphatase(ALP),acid phosphatase(ACP),malondialdehyde(MDA)and hemocyanin(Hc)than other two treatment;among these indcies,only significant difference was found on malondialdehyde(MDA);(4)During the pathogen challenge test within 12-96 h,traditional diets treatment(TD)had the higher cumulative mortality than the other two groups in both males and females;the similar cumulative mortality was detected for the males of formulated diets treatment(FD)and mixture diets treatment(MD)while the cumulative mortality of mixture diets treatment(MD)females was between formulated diets treatment(FD)and traditional diets treatment(TD).In conclusion,feeding of formulated diets can improve the early culture performance,immunity and the survival during the pathogen challenge test of juvenile E.sinensis,which suggested our optimized formulated diets could improve the quality of crabseeds for Chinese mitten crab.