No abstract

The effect of increasing levels of dietary phospholipids (PL) on the ovarian development and reproductive performance of Chinese mitten crab Eriocheir sinensis were investigated using four semipurified formulated diets supplemented with 0%, 1.2%, 2.4%, and 3.6% PL. Four groups of 40 females, with an average individual body weight of 95-120 g, were fed the experimental diets for a period of 7 months. Male crabs were introduced into the female rearing system in March, and mating, spawning, and egg hatching occurred in the following month. After 10 weeks of feeding, females fed the diet with 2.4% PL had a significantly higher gonadosomatic index (GSI) than females fed the diet with 0% PL, whereas females fed the diet with 1.2% PL had a significantly higher hepatic moisture content and lower hepatic lipid content than the other groups (P \ 0.05). After mating, the spawning rate was higher among females fed diets with 3.6% and 2.4% PL (95% and 92%, respectively) compared with females fed diets with 0% and 1.2% PL (both 81%). The results showed that egg production (total number of eggs/female) and fecundity increased with increasing dietary PL level, with females fed diets with 0% and 1.2% PL supplementation having significantly lower values than females fed the diet with 3.6% PL (P \ 0.05). In conclusion, our results suggest that dietary PL supplementation has a positive effect on ovarian development and reproductive performance of E. sinensis broodstock. Further study should aim to investigate the optimal PL level in the broodstock diet of E. sinensis in respect to offspring quality.

This study was conducted to determine the optimum highly unsaturated fatty acid (HUFA) level in semi-purified diets for female Chinese mitten crab Eriocheir sinensis broodstock. Five isolipidic and isonitrogenous diets were formulated to contain different HUFA levels (0.14, 0.65, 1.15, 1.64, and 2.07%, respectively) by the supplementation of HUFA-rich fish oil. Diets were fed to triplicate groups of 25 female crabs (75 animals per treatment) stocked in concrete tanks for 8 months. The hepatopancreas, ovary, and muscle of the crabs were sampled after 3-month culturing, and the eggs were sampled after 8-month culturing. The reproductive performance of E. sinensis broodstock was evaluated in relation to the different dietary HUFA levels. Moreover, the fatty acid composition of the hepatopancreas, ovary, muscle, and eggs was determined in crabs fed various levels of HUFA. The results showed that a significant positive correlation was observed between the dietary HUFA level and the HUFA content in hepatopancreas, ovary, and egg, respectively. However, no significant difference in gonadosomatic index, hepatosomatic index, and total ovarian and hepatopancreatic lipid content among the treatments was observed after 3-month culturing. Also, the reproductive performance was similar for all treatments after 8-month culturing. The fact of lacking significant correlation between reproductive parameters and dietary HUFA level was discussed in respect of the catadromous life cycle of E. sinensis and warranted further research with more comprehensive approaches