Study On The Production And Quality Of Different Strains Of Eriocheir Sinensis Based On The Closed-loop Ecosystem Of "Three Ponds And Two Dams"

In this experiment,five strains of E.sinensis crab were cultured in a closed-loop ecosystem of"three ponds and two dams" in Heilan County,Ningxia Diversion Irrigation District,and the growth of different strains of Eriocheir sinensis was observed on the basis of the characteristics of water quality and aquatic plant growth during the culture period.The amino acid and volatile substance composition of each strain of Eriocheir sinensis was measured and studied during the maturation period,so as to evaluate the breeding effect of each strain of Eriocheir sinensis in Yinchuan area.The study was conducted to provide some data and theoretical references for the introduction of Eriocheir sinensis in Yinchuan irrigation area.The specific results of the study are as follows:(1)The water quality in the closed-loop system of "three ponds and two dams" was significantly improved during the flow from the inlet to the outlet,and the system had a strong effect on water purification.The biological index of mint was found to be suitable for the growth of mint,and the growth of mint helps to degrade and eliminate some nutrients in the culture water to improve the water body.(2)The average weight of male adult Eriocheir sinensis in the five strains was 65.86 g,body length was 50.79 mm and body width was 53.48 mm,while the average weight of female adult crab was 57.12 g,body length was 47.52 mm and body width was 50.81 mm,and overall the average size of male individuals was higher than that of females.The growth characteristics of Xuancheng crab,which had the largest adult size,were different from the other four groups in that its growth was slow in the early stage but fast in the later stage.The relationships between the growth data of female and male Eriocheir sinensis of each strain were fitted and found that,on the whole,female body weight was a power function of body length and body width;among male crabs,only Xuancheng crab had a linear function of body weight and body length;the male Heran crab had a logarithmic function of body weight and body width,and a linear function of body length and body width;Xuancheng crab had a power function of body length and body width.(3)The amino acid species isolated from the muscle and gonads of the five strains of Eriocheir sinensis were basically the same in the female and male groups,and the total amino acid quantity of the female crab was higher than that of the male crab.The amino acid contents of muscle,Arg and Lys were higher in all groups;the amino acid contents of gonad were higher in Glu,Asp,Arg and Leu,and the overall amino acid contents of gonad were significantly lower than those of muscle;it was found that the first limiting amino acids of muscle and gonad were Met+Cys in all strains of E.sinensis.The amino acid branched chain/aromatic value of the male crab muscle of Xuancheng crab and Shuiyang crab was close to the egg protein standard,and the protein quality was the best.(4)A total of 42 volatile substances were detected in the muscle of female E.sinensis from the five strains,and 28 were identified,with the highest relative content of phenolic compounds,followed by nitrile amines and other heterocyclic compounds.The volatile substances were detected in male crab muscle samples.The most abundant volatile substances were found in the muscle of Sheyang crab and Panjin crab.A total of 55 volatile substances were detected in the gonads of female crabs,and 41 were identified.Among the alcohols,2,6-nonadienol was unique to the gonads of female crabs.A total of 52 volatile substances were detected in the gonads of male crabs,and 41 were identified.4-Terpene alcohols were unique to the male gonads.The most abundant volatile substances were found in the gonads of Xuancheng crab and Panjim crab.Overall,both Xuancheng crab and Panjin crab had good farming performance,but the yield of Xuancheng crab was slightly lower per mu,presumably due to the mismatch of farming techniques,which may improve the farming techniques at a later stage to make their farming prospects more promising.