Studies On The Growth,nutritional Quality And Digestive Physiology Of Eriocheir Sinensis Under Rice-crab Culture Systems

The development of rice field crab culture in northern China started late,which is still dominated by extensive culture,lacking relevant basic information such as growth rules,nutritional needs and fattening techniques.Therefore,exploring the growth law and physiological changes of Eriocheir sinensis(E.sinensis)can provide theoretical reference for precise nutritional needs and reasonable fattening of raised in rice field in northern China.In this experiment,E.sinensis was used as the experimental animal,three independent rice fields with an same area(996 m~2)were selected for 62 day feeding rice field culture model.Crab samples,etc.were collected on day 0(July 15,T0 period),day 15(July 30th,T1 period),day31(August 15th,T2 period),day 46(August 30th,T3 period)and day 62(September 15th,T4period)of the culture experiment.Through the detection of E.sinensis growth performance,edible nutritional quality,intestinal digestion indicators to compared the changes of growth performance,nutritional quality of edible parts and digestive physiology of crab in different growth periods.The results are as follows:1.Growth performance of E.sinensis in rice-crab co-culture system at different developmental periodsFemale E.sinensis:HSI reached the maximum at T1 period;ovary began to develop at the T2 period,and GSI reached their peak at T4 period;MY and TEY reached their peak at T3period;CF at T4 period was significantly higher than the other periods(P<0.05);WG,WGR and SGR were significantly higher from T1 to T3 periods than that of other periods(P<0.05).Male E.sinensis:HSI and GSI reach maximum values at T0 and T4 period,respectively;MY,TEY and CF were significantly higher at T4 period than those of the T0-T2 periods(P<0.05);WG,WGR and SGR reached their peak at T2 and T3 periods.Female E.sinensis:The serum GH and 20-HE content reached their maximum at T3 and T2 periods,respectively.Male E.sinensis:The serum GH and 20-HE content reached their maximum at T3 and T4 periods,respectively and were significantly higher than those at T0,T1 and T2 periods(P<0.05).Female E.sinensis:The muscle Ec R,RXR,IGF2 and CHI m RNA expression level all reached the their maximum at T2 period,and the IGF2 and CHI m RNA expression levels were significantly higher than the other periods(P<0.05).Male E.sinensis:The muscle Ec R,RXR and IGF2 m RNA expression level reached the maximum at T3 period;there was no significant difference in CHI m RNA expression among different periods(P>0.05).2.Nutritional composition of E.sinensis in rice-crab co-culture system at different developmental periodsFemale E.sinensis:The crude protein content of muscle,hepatopancreas and ovary reached the maximum at T4,T0 and T4 periods,respectively;the crude lipids content of hepatopancreas and ovary reached the maximum value at T1 and T4 periods respectively.Male E.sinensis:the crude protein content of hepatopancreas and gonad reached the maximum value at T2 and T3 periods,respectively;the crude lipids content of hepatopancreas and gonad reached the maximum value at T3 and T4 periods,respectively.Female E.sinensis:the∑EAA content of muscle reached the maximum value at T3period;the∑TAA contents of muscle at T2,T3 and T4 periods were significantly higher than those of the T0 period(P<0.05);the contents of∑EAA and TAA in hepatopancreas from T2to T4 period were significantly lower than those at T0 and T1 periods(P<0.05);the contents of∑EAA and∑TAA in ovary reached the maximum value at T3 period;the EAA/TAA ratio of ovary at T3 and T4 periods were significantly higher than that at T2 period(P<0.05).Male E.sinensis:the contents of∑TAA and∑EAA in hepatopancreas reached the maximum value at T2 period;the contents of∑TAA and∑EAA in gonads at T4 period was significantly higher than those at T0-T2 periods(P<0.05).Female E.sinensis:∑PUFA and∑n-3PUFA,and n3/n6 in muscle from T2 to T4 periods were significantly lower than those at T0 and T1 periods;the contents of∑PUFA,∑n-3PUFA and∑n-6PUFA and the ratio of n3/n6 in hepatopancreas reached the maximum value at T2period;the contents of∑PUFA and∑n-3PUFA and the ratio of n3/n6 in ovary in T3 and T4periods were significantly lower than those at T2 period(P<0.05).Male E.sinensis:the content of the ratio of n3/n6 in muscle during T1-T4 periods were significantly lower than those at T0 period(P<0.05);the contents of∑PUFA and∑n-3PUFA in muscle during T2-T4periods were significantly lower than those at T0 and T1 periods(P<0.05);the contents of∑PUFA and∑n-6PUFA in hepatopancreas reached the maximum at T3 period,the contents of∑n-3PUFA and the ratio of n3/n6 in hepatopancreas reached the maximum at T1 period;the contents of∑PUFA,∑n-3PUFA and∑n-6PUFA and the ratio of n3/n6 in gonads at T3 and T4periods were significantly lower than those at T2 period(P<0.05).3.Digestive physiology of E.sinensis in rice-crab co-culture system at different developmental periodsFemale E.sinensis:intestinal lipase activity at T1 and T2 periods were significantly higher than those of other periods(P<0.05);intestinal trypsin and amylase activity at T2period which were significantly higher than T1,T3 and T4 periods;hepatopancreas amylase activity reached the maximum value at T2 period,hepatopancreas lipase and trypsin activity at T4 period were significantly lower than T0,T1 and T2 periods(P<0.05).Male E.sinensis:intestinal lipase and trypsin activities at T3 period were significantly lower than those of other periods(P<0.05);hepatopancreatic lipase and trypsin activities at T4 period were significantly lower than those of other periods(P<0.05).Female E.sinensis:the m RNA expressions level of intestinal PRS44 and CTRB1,intestinal and hepatopancreas TGL at T2 period were significantly higher than those of other periods(P<0.05);the m RNA expression level of intestinal and hepatopancreas IL and hepatopancreas TRYP duing T2-T4 periods were significantly higher than T0 and T1 periods.Male E.sinensis:the m RNA expressions level of intestine TGL,CTRB1 and TRYP at T3period was significantly higher than those of other periods(P<0.05);the m RNA expressions level of intestinal PRS44 during T2-T4 periods were significantly higher than those of T0 and T1 periods(P<0.05);the m RNA expressions level of hepatopancreas TGL,CTRB1,PRS44and TRYP at T2 and T3 periods were significantly higher than those of other periods(P<0.05).Female E.sinensis:Tenericutes abundances at the T2-T4 periods were significantly higher than T0 and T1 periods(P<0.05);Proteobacteria abundances at the T1-T4 periods were significantly lower than T0 periods(P<0.05);Firmicutes and Bacteroidetes reached the maximum abundances at T1 and T4 period,respectively.Candidatus＿Hepatoplasma abundance at T4 period was significantly higher than those of other periods(P<0.05).Male E.sinensis:The abundance of Tenericutes at T3 and T4 periods was significantly higher than T0-T2 periods(P<0.05).Firmicutes abundance at the T1 period was significantly higher than those of other periods(P<0.05);Proteobacteria and Bacteroidetes reached the maximum abundances at T0 and T2 period,respectively.The abundance of Candidatus＿Bacilloplasma at T3 period were significantly higher than those of other periods(P<0.05).The abundance of Bacteroides at T2 period was significantly increased(P<0.05).Under the rice-crab culture system in Jilin Province,the rapid period of growth and tissue development of rice crab is in August,we suggest that the feeding amount should be increased in August to ensure the nutritional requirements for the rapid growth and development of rice field crabs.the male and female E.sinensis have different gonad development starting points;the male crab(July 15)is earlier than the female E.sinensis(August 15),recommended to appropriate supplement fattening feed in mid-late July;during the period from August 15 to August 30,the gonad of rice field crab develops rapidly,and the ability of nutrient deposition and digestion is strong.At this time,sufficient feeding of breeding fertilizer should be ensured.At this stage,the gonad develops rapidly,and the quality of breeding fertilizer should be properly improved.The nutritional structure of breeding fertilizer should be adjusted in time.