The effect of intermittent starvation on growth performance, precocity, digestive enzyme activity, and body chemical composition of juvenile Chinese mitten crab Eriocheir sinensis

The effects of intermittent starvation on the growth, precocity, digestive enzyme activity, feeding, and body chemical composition of the juvenile Chinese mitten crab Eriocheir sinensis were investigated in two independent experiments. Crabs were reared individually during Experiment I and cultured in aggregate during Experiment II. Five treatments were tested in both experiments. Crabs in the control group (Group C) were fed continuously and, in Groups S3, S6, S10, and S15, were starved and then re-fed for 3, 6, 10, and 15 days, respectively. The precocity rate of Group C was significantly higher than that of the other groups. In Experiment I, the final mean body weight and the mean specific growth rate in dry matter of Groups C and S3 were significantly higher than those of the other groups. In Experiment II, the mean specific growth rate in body weight in Group C was similar to that of Groups S3, S6, and S10 but significantly higher than that of Group S15. Crabs in Groups S3, S6, and S10 compensated for starvation-induced growth depression after being re-fed, and compensatory growth was achieved via both higher feeding rate and improved feed efficiency. There was no significant difference in trypsin and alkaline phosphatase activity, while steapsin and amylase activity were significantly affected by the starvation period. There was no significant difference in dry matter, ash, and protein content among Groups C, S3, S6, and S10 in Experiment I. The results demonstrated that proper intermittent starvation was sufficient for reducing the precocity rate of cultured juvenile E. sinensis, and it is recommended that juvenile crabs be subjected to intermittent fasting for 6 to 10 days to maintain precocity rates at acceptable levels without inhibiting growth and yield.