Growth performance, gonad development and nutritional composition of Chinese mitten crab Eriocheir sinensis selected for growth and different maturity time

Chinese mitten crab is an important aquaculture species in China, and a selective breeding program has been operated for the economic traits of growth and different maturity time of this species since 2010. This study aimed to evaluate the growth performance and nutritional composition of two selected lines, i.e. early-maturing strain (EM) and late-maturing strain (LM), and control population without genetic selection cultured in identical outdoor earth ponds. The results showed that (1) The average body weight of two selective lines were always higher than the control during the pond culture of adult E. sinensis. Among two selected lines, the average body weight of the EM was relatively higher than that of LM between May and July, but EM had the relatively lower body weight than the LM during the late culture stage between Sept and Nov. (2) Compared to control population, despite of males or females, pubertal molting of EM and LM were occurred earlier and later respectively than that of control both, and there were around 15-20 days earlier for the pubertal molting of EM. For gonadosomatic index (GSI), EM had the higher GSI than LM and control populations between Oct.10 and Nov. 20 for males as well as between Sep.20 and Oct 30 for females during the gonadal development cycle; (3) For the edible indices of adult crabs at the harvest, EM had the significantly higher of GSI and total edible yield (TEY) than LM, and control had the lowest hepatosomatic index among three populations (P < .05); (4) For proximate composition, three populations generally had the close proximate contents in three edible tissues (muscle, gonads and hepatopancreas), but female LM had the significantly lower lipid contents in both hepatopancreas and gonad than EM and control (P < .05); (5) As for fatty acid, female LM had the higher percentages of C18:3n3, total polyunsaturated fatty acids (EPUFA) and total long chain polyunsaturated fatty acids (E LC-PUFA) in muscle and hepatopancreas than the other populations, while EM had the significantly higher percentages of C22:6n3 in gonads than LM for both males and females; (6) Selective breeding had no apparent effects on amino acid compositions and contents of muscle and all essential amino acid scores were above 100. In summary, selective breeding provides a useful means for the improvement of growth and time of pubertal molting for E. sinensis, but has limited effects on their nutritional composition.