Effects of fattening period on ovarian development and nutritional quality of adult female Chinese mitten crab Eriocheir sinensis

The fattening of immature female Chinese mitten crab (Eriocheir sinensis) with high quality diets is an effective mechanism for improving ovarian development and nutritional quality. This study investigated the ovarian development and nutritional quality of female E. sinensis during an 80-day fattening period. The results showed that the gonadosomatic index (GSI) and total edible yield of female E. sinensis increased in a stepwise manner over the course of the fattening period, in synchrony with a decrease in feed consumption and feed cost. Crude protein, total lipid and total carbohydrate in ovaries increased significantly over the course of the fattening period, with the highest crude protein content in both the hepatopancreas and meat observed at Day 40. There was a stepwise increased in the content of triacylglycerol (TAG) and cholesterol (CHO) and phospholipid (PL) in ovary and meat, respectively. On the contrary, the content of free fatty acid (FFA) and PL in ovaries and hepatopancreas as well as the meat TAG and FFA decreased significantly over the course of the fattening period. In ovaries, the highest concentration of polyunsaturated fatty acid (∑PUFA) was observed at Day 60, whilst the highest total monounsaturated fatty acid (∑MUFA) in meat was detected at Day 40. The highest content of ∑MUFA in hepatopancreas, and the ∑PUFA and total long chain polyunsaturated fatty acid (∑LC-PUFA) in meat were detected at Day 80, while the highest hepatopancreas ∑PUFA was detected at Day 0. The content of total essential amino acids (∑EAA) and total amino acids (TAA) in ovaries and meat increased significantly during the fattening period of Day 0 to Day 40, while no significant increase was detected on the TAA during the period of Day 40 to Day 80. Essential amino acid scores (EAAS) of ovary and meat were >100 for all essential amino acids (EAA), and fattening culture did not significantly improve EAAS for ovary and meat. In conclusion, the fattening could improve the total edible yield and nutritional values of female E. sinensis. Considering the fattening performance and feed cost, the appropriate fattening period should be 40–60 days for pond-reared female E. sinensis post puberty molting.