| The ridge-tailed white shrimp(Exopalaemon carinicauda)holds eggs many times a year,but there are problems of uneven individual development maturity and unsynchronized gonadal development,so the large-scale seedling breeding technology has not been established.Based on this,this study attempts to artificially promote ripe gonads way makes the morphological and the gonad synchronous development of E.carinicauda,in order to reduce the consumption of manpower and financial resources,in combination with a lot of the same type of research,this study chose natural algae powder(Schizochytrium,Porphyridium cruentum),and the neurotransmitters(5-hydroxytryptamine)as additive,according to the orthogonal experiment,the method of design for 16 group feed,16 groups of diets were fed to females and males of E.carinicauda,respectively,with the concentrations of Schizochytrium powder(0,3%,6%,9%),P.cruentum powder(0,0.5%,1%,2%)and 5-HT creatinine sulfate(0,0.0025%,0.005%,0.01%).To explore the effects of three kinds of feed additives on gonad development of E.carinicauda,the main results are as follows:(1)Effects of different dietary supplements on gonadal development of female E.carinicauda: Female E.carinicauda with a size of(1.49 ± 0.12)g were cultured for 4 weeks.The results showed that the specific growth rate of female E.carinicauda in S7 group was higher than that in other experimental groups.The survival rate of female E.carinicauda in S8group(Schizochytrium powder 6%,P.cruentum powder 0,5-HT sulfate 0.005%)was the highest,reaching 96.67%,when fed with the diet of S7 group(Schizochytrium powder 3%,P.cruentum powder 2%,5-HT sulfate 0).In terms of gonadal development,the gonadal index of S10 group(Schizochytrium powder 6%,P.cruentum powder 1%,5-HT sulfate 0.0025%)was significantly higher than that of other groups(P<0.05),and the ovarian development rate was the highest(79.30±2.64)%.The optimal feed ratio obtained by orthogonal analysis of gonad index is that of S10.Meanwhile,the concentrations of total protein(TP),triglyceride(TG)and cholesterol(T-CHO)in haemolymph of female E.carinicauda in S10 group were the highest,and the final contents of gonadotropin-releasing hormone(Gn Rh)in haemolymph,ovarian vitellogenin(VTG)and estradiol(E2)in S10 group were significantly higher than those in other groups(P<0.05).Diet in S7 group(Schizochytrium powder 3%,P.cruentum powder 2%,5-HT sulfate 0)is the most beneficial to the growth of female E.carinicauda.The diet in S10 group(Schizochytrium powder 6%,P.cruentum powder 1%,5-HT sulfate 0.0025%)was most beneficial to the gonad development of female E.carinicauda.(2)Effects of different dietary supplements on gonad development of male E.carinicauda:Male E.carinicauda with a size of(1.36±0.20)g were cultured for 4 weeks.The results showed as follows: the specific growth rate(SGR)and weight gain rate(WGR)of male E.carinicauda in S3 group fed diets(Schizochytrium powder 0,P.cruentum powder 2%,5-HT sulfate0.0025%)were higher than those in other groups,and there was no significant difference in survival rate among all groups(P>0.05).In terms of gonadal development,the gonadal index of S12 group(Schizochytrium powder 9%,P.cruentum powder 0,5-HT sulfate 0.01%)was higher than that of other groups but not significantly(P>0.05),and there was no significant difference in sperm survival rate among groups(P>0.05).The results of orthogonal analysis of gonadal index showed that the optimal diet ratio was(Schizochytrium powder 6%,P.cruentum powder0,5-HT sulfate 0.01%),and there was no significant difference in gonadal index with S12group(P>0.05).The concentrations of TG and T-CHO in hemolymph of male E.carinicauda in S12 group were the highest,but there was no significant difference compared with other groups(P>0.05),and the final activities of total ATPase and lactate dehydrogenase(LDH)in sperm in S12 group were higher than those in other groups(P<0.05).The diet of S3 group(Schizochytrium powder 0,P.cruentum powder 2%,5-HT sulfate0.0025%)is the most beneficial to the growth of male E.carinicauda.The diet in group S12 improved the enzyme activity of sperm and was most beneficial to the gonad development of male E.carinicauda.However,the combination experiment results obtained by orthogonal analysis showed no significant difference with that in group S12.The following proportions were optimal for promoting the development of male gonads in E.carinicauda(Schizochytrium powder 6%,P.cruentum powder 0,5-HT sulfate 0.01%).(3)Effects of DHA and ARA as substitute for natural feed additives on gonad development of E.carinicauda female shrimp(2.52±0.30)g and male shrimp(1.93±0.34)g,respectively,were used as breeding subjects.The optimal diet for promoting the development of male and female gonads of E.carinicauda was replaced by pure fatty acid DHA and ARA,and the culture experiment lasted for 4 weeks.The results showed that there was no significant difference in gonad index and ovarian development rate(sperm survival rate)between male and female groups.There were significant differences in hemlymphoid biochemical parameters of female shrimp between the two groups.However,compared with T10 group(DHA:0.2268066%,ARA: 0.0001733%,5-HT sulfate 0.0025%),and the contents of Gn Rh and VTG in group A10(Schizochytrium powder 6%,P.cruentum powder 1%,5-HT sulfate 0.0025%)were significantly higher than those in group T10 on 28d(P<0.05);There was a significant difference in the serum TG concentration between the two groups,while there was no significant difference in TP and T-CHO concentration(P>0.05),and the change trend was consistent.The testosterone(T)content in the blood lymphocytes of male shrimps fed diets in group A12(Schizochytrium powder 6%,P.cruentum powder 0,5-HT sulfate 0.01%)was higher than that in group T12(DHA: 0.2268%,ARA: 0.0001656%,5-HT sulfate 0.0025%),but there was no significant difference between the two groups(P>0.05),the final sperm LDH activity in A12 group was significantly higher than that in T12 group,and the ultrafine total ATPase activity changed significantly.The two groups had significant effects on the hepatopancreas digestive enzyme activities of male and female E.carinicauda(P<0.05),but the changes of the effects were not regular.Gonadal inhibitory hormone gene GIH was highly expressed in all tissues except spermatozoa of E.carinicauda in pure substance group,and there was significant difference(P<0.05).The expression of Molting inhibitory hormone gene MIH was also high in all tissues of E.carinicauda in pure matter group,and there were significant differences in female hepatopancreas and eye stalk,male sperm and eye stalk(P<0.05).Diet in group A10 can increase the nutrient and hormone accumulation of female E.carinicauda,and significantly decrease the expression of MIH and GIH genes.Group A12 can increase the sperm enzyme activity of male E.carinicauda,and significantly reduce the expression of MIH and GIH genes(P<0.05).Considering the feed effect and economic benefit,The most favorable diet for gonadal development of female E.carinicauda was group A10(Schizochytrium powder 6%,P.cruentum powder 1%,5-HT sulfate 0.0025%).The most favorable diet for male gonad development of E.carinicauda was group A12(Schizochytrium powder 6%,P.cruentum powder 0,5-HT sulfate 0.01%).This paper has 28 figures,13 tables and 127 references. |
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