| Chinese mitten crab(Eriocheir sinensis,hereinafter referred to as E.sinensis)is an important economic aquatic animal and also a traditional delicacy food in China.With the continuous expansion of large-scale and intensive breeding of E.sinensis,the scale of the industry has also expanded.With the expansion of scale and non-standard artificial breeding,problems such as germplasm degradation,environmental pollution,and reduced efficiency have been caused,which seriously restrict the healthy and sustainable development of the industry.This has also led to a variety of researches on improving the healthy development of the industry.Carotenoids are important pigments of vitamin A precursors in the natural world,and have functions such as anti-oxidation,immunity enhancement,and aquatic product quality enhancement.Crustaceans can not synthesize carotenoids themselves and can only rely on ingestion of exogenous foods.In recent years,they have been added as exogenous additives to E.sinensis feed to improve their quality,but under the premise of large-scale breeding,E.sinensis changes in carotenoid content in the body and its effect on actual production have not been reported.Therefore,in this study,we investigated the carotenoids content and related energy substances of E.sinensis embryos to megalopa Ⅴ period,at the same time but different morphological,Pre and post-overwintering of first-instar juvenile E.sinensis,to explore the carotenoids affect E.sinensis actual production.1.Changes of carotenoid content from embryonic to megalopa of E.sinensisSamples of late-stage embryos,stage I-IV of zoea,megalopa stages I and V of E.sinensis and late-opening bait samples were collected on April 26 th to May 12 th,2017.The contents of crude protein,total lipids,and four kinds of carotenoids(astaxanthin,canthaxanthin,lutein,and β-carotene)in samples were determined by kjeldahl method,Folch chloroform methanol method,and LC-MS/MS.The purpose of this experiment was to investigate the energy consumption preference and carotenoids content changes at each stage during the development of embryonic moltings to megalopa,aiming to provide evidence of energy and carotenoid supplements for the E.sinensis parent breeding,fry hatching and fry to crab stage.The results showed that:(1)Protein content of E.sinensis decreased significantly during the period from embryonic incubation to zoea stage I,from zoea stage V to megalopa stage I(P<0.05),and significant increase in megalopa stages I to V was observed.(P<0.05),No significant change in other periods of E.sinensis,opening bait protein content was Rotifer>Opossum shrimp>Artemia;(2)Total lipid content in the embryo stage of E.sinensis was the highest,the lowest was in the megalopa stage V.The total lipid content in the embryo to the zoea stage I,in the zoea from stage III to IV,and from the zoea stage V to the the megalopa stage V were decreased significantly(P<0.05),but increase significantly during zoea stage IV to V(P<0.05).There was no significant change in other periods.The total lipid was Opossum shrimp>Rotifer>Artemia;(3)During embryonic development of molting to megalopa,β-carotene was not detected.The contents of canthaxanthin,lutein and astaxanthin all showed a trend of increased firstly and then decreasing.The content of canthaxanthin and lutein was the highest in the zoea stage II,and the content was lowest in the zoea stage I and V.Astaxanthin content in the zoea stage III and I was the maximum and minimum.The content of canthaxanthin and astaxanthin were increased significantly from zoea stage I to II(P<0.01),and canthaxanthin content was decreased significantly from zoea stage II to megalopa stage I(P<0.05).Lutein content was decreased significantly in zoea stage II to IV(P<0.05).There was no significant change in the content of astaxanthin after zoea stage IV.The open bait canthaxanthin and astaxanthin content was Rotifer>Artemia>Opossum shrimp,lutein content was Artemia>Rotifer>Opossum shrimp;(4)Research shows that during period of the embryonic development of molting to megalopa of E.sinensis main use the fetal energy firstly,then was the lipid.Lipid consumption was accompanied by oxidative decomposition,which was involved in the carotene as an important antioxidant and an important pigment against stress,and tends to be stable after the stage II or III,pathways of the zoea are activated and gradually depleted.In the parental cultivation phase,pay attention to nutritional enhancement to maintain adequate fetal energy storage during the embryonic stage and to stage the supplemental exogenous energy levels and carotenoids after embryonic incubation to increase the hatching success rate and later development of the juvenile E.sinensis to deal with complex environmental stresses has important significance.2.Changes of carotenoid and fatty acid contents in different morphological type juvenile crabs of juvenile E.sinensis at the first instarThe six groups of first-instar juvenile E.sinensis were collected from the same period in Chongming District of Shanghai on January 16,2018,and the body weights were(0.30±0.01)g,(1.28±0.13)g,(2.28,respectively).± 0.19)g,(5.04 ± 0.08)g,(8.05 ± 0.11)g,(18.88 ± 0.15)g,were recorded in groups A,B,C,D,E,and F.The contents of crude protein,total lipids,fatty acids,and four carotenoids(astaxanthin,canthaxanthin,lutein,and β-carotene)of the sample were determined by Kjeldahl method,Folch chloroform methanol method,GC-MS,and LC-MS/MS.The purpose of this study was to explore the causes of different shapes of the E.sinensis in the same period and the differences in the quality of different morphotypes.The results showed that:(1)Hepatopancreatic index E>D>C>F>B>A,the overall hepatopancreas index increased with the morphology increasing,and more gradient experiments were needed between group E and F.(2)There was no significant difference in protein content in different morphotypes of cephalothorax.There was no significant difference in protein content between group D and E in hepatopancreas but has significant difference with group F(P<0.05).Total lipid contents of hepatopancreas was F>D>E >B>C>A,the overall trend is upward,the greater the morphology,the higher the total lipid content.There was a significant difference between group A and E(P<0.01);(3)With the increase of morphotype,the content of saturated fatty acid(SFA)decreased significantly,the monounsaturated fatty acid(MUFA)increased significantly,and there was no significant change in the polyunsaturated fatty acid(PUFA).Among them,C16:0,C18:0 in SFA,C18:3n3,and C20:5n3 in PUFA may be consumed as the main energy fatty acids with increasing body size,and the content is decreased significantly with the increase of morphology(P<0.05).C18:1n9,C18:1n7 in MUFA may be stored as late functional fatty acids,and the content is significantly increased(P<0.05);(4)The content of carotenoids in six groups of morphological cephalothorax and hepatopancreas showed different changes.Astaxanthin and β-carotene in the cephalothorax showed an upward trend,but canthaxanthin and lutein showed a trend of decreasing firstly and then increasing.The astaxanthin and β-carotene in the hepatopancreas showed a decreasing trend,The content of canthaxanthin increased with the increase of morphology(P<0.05).It may be due to the increase of hepatopancreas that enhances the ability of canthaxanthin accumulation;(5)In summary,in order to improve the efficiency of adult crab breeding,the authors believe that it is more appropriate to choose the first-instar juvenile E.sinensis with similar morphology to the group E as the crab species.3.Changes of fatty acids and four kinds of carotenoids contents of the first-instar juvenile E.sinensis pre and post-overwinteringSamples were taken on December 5,2016 and March 1,2017 respectively,and the contents of fatty acids and carotenoids were determined by HPLC and LC-MS/MS.This article compared and analyzed changes in body(internal)fatty acids and four kinds of carotenoids(astaxanthin,canthaxanthin,lutein,and β-carotene)in the first-instar juvenile E.sinensis,Chongming,Shanghai.This study was to explore whether the first-instar juvenile E.sinensis are feeding briefly overwinter,and whether the method of judging the quality of the E.sinensis through hepatopancreas color was reliable.The results showed that:(1)In the fatty acid composition of first-instar juvenile E.sinensis,saturated fatty acids(SFA)C20:0 and monounsaturated fatty acids(MUFA)C18:1n9 in the hepatopancreas were used as main energy fatty acids for passive use,its content decreased significantly post-overwintering(P<0.05),and C18:3n3 and C22:6n3 in polyunsaturated fatty acids(PUFA)increased significantly post-overwintering(P<0.05).(2)SFA:C16:0,C18:0 in cephalothorax,and C18:1n7 in MUFA were used as the main energy fatty acids,which decreased significantly post-wintering(P<0.05).The content of PUFA C18:2n6 and C20:3n6 increased significantly post-wintering(P<0.05).(3)Post-wintering,the contents of carotenoids in cephalothorax were decreased significantly(P<0.01).Among them,the content of astaxanthin and lutein in the hemolymph was increased significantly(P<0.05),and the content of β-carotene was decreased significantly(P<0.05).The changes of astaxanthin,lutein and β-carotene in the hepatopancreas were consistent with those in the hemolymph,and the content of canthaxanthin was decreased significantly(P<0.05).(4)The transient increase in temperature and water temperature overwintering may cause short-term ingestion of first-instar juvenile E.sinensis.(5)The color change of hepatopancreas was mainly caused by pigment composition and changes in the content of four kinds of carotenoids,pre and post-overwintering.According to the color of hepatopancreas to judge the quality of juvenile E.sinensis post-overwinter is worth considering and needs further study. |
PDF Full Text Request