Effects Of Environmental And Nutritional Factors On Development And Precociousness Of Procambarus Clarkii

Procambarus clarkii belongs to Crustacea,Decapoda,Reptantia,Cambaridae,Procambarus,also named Red Swamp Crayfish or freshwater lobster.P.clarkii has become an important aquatic resources.research indicate that P.clarkii is abundant in eight essential amino acids,protein and Fat accounting for 18.9 and 1.6 percent of the fresh weight respectively.in addition,Its hepatopancreas also calledc"xiahuang",rich in unsaturated fatty acids,protein,free amino acids and trace elements such as selenium,is also a titbit.owing to its delicious flavor,high nutrient value and the increasing consumption,The demand for these goods Exceeds the supply.however,at present there are two prominent problems posing great threaten to the cultivation of P.clarkii,First,the lack of P.clarkii larvae,this problem has become the bottleneck the development of Aquaculture industry of P.clarkii,Artificial breeding is believed a effective way to solve the problem,however,because of the high Molting frequency and the weak disease resistance in larvae stage,mortality rate is often happened in breeding.therefor,exploring the nutrient requirements and developing formulated feed to promote its survival and growth rate of P.clarkii larvae are very important.Second,precociousness of P.clarkii,Similar to Eriocheir sinensis,precocious ones are usually smaller than the normal ones.while the unite price of precocious ones is several times lower than that of normal ones,high proportion of Precociousness brings farmers a huge loss of wealth.To solve the two problems,we made some research,the results were reviewed reviewed as follows.1.The effect of vitamin A(VA),vitamin C(VC),vitamin E(VE)on survival,growth,antioxidant capacity and immunity of P.clarkii.by using the L18(3)table of orthogonal rotation design,we designed 18 kinds of diets and feed two-month old P.clarkii respectively.The results showed that,a higher survival and weight gain rates were occurred when VA,VC,VE Supplementations was 0.006%,0.02%,0.04%respectively,which is the optimum dietary combinations of VA,VC,VE.in addition,we determined the content of Malondialdehyde(MDA)and Specific activity of Superoxide Dismutase(SOD)in hepatopancreas and Phenol oxidase(PO)in gill of P.clarkii.The results showed the content of MDA and specific activity of Superoxide Dismutase(SOD)in hepatopancreas is a reflection of an important proxy for the health of P.clarkii.And there is a complex interrelation between the function of VA,VC,VE.2.Effect of water temperature,stocking density and different proportion between fish meal(FM)and soybean meal(SM)on the survival rate and weight gain rate,precociousness(taking gonadosomatic index and mature rate as indexs)of P.clarkii.we conducted this experiment by choosing green carapace and body weight 9.83±0.09g(mean±SE)of P.clarkii as experimental animals and using the L9(34)table design,the result showed that relatively high water temperature can promote the growth,while it can be a disadvantage to the survival rate.Relatively low stocking density is conductive to the survival rate and growth,While the influence to any of these indicators of FM:SM did not reach significant lever.Study of effect of three factors on precociousness showed that the order was water temperature>stocking density>FM:SM.The results indicated that relatively low water temperature can arrested growth but at the time promote the development of ovary.Relatively high stocking density and FM:SM also contribute to precociousness.3.We chose early maturity of P.clarkii(GSI:2.79,2.95,2.97 respectively)and the normal ones(GSI:0.423,0.730,0.606 respectively)as experimental material,then constructed two-directed Full-Length Normalization Subtractive Hybridization(FNSH).cDNA sequence of some genes was obtained which lay a foundation for screening early related genes and understanding expression regulation mechanism.