Effects of feeding frequency and food type on growth and energy budget of juvenile Chinese mitten crab Eriocheir sinensis

A 48-day feeding experiment was carried out to investigate the effects of feeding frequency( once a day,twice a day,and three times a day) and food types( formulated diets and fresh trash fish) on growth and energy budget of juvenile Chinese mitten crab Eriocheir sinensis with initial body weight of( 4.96 ± 0.08) g at water temperature of 18-22 ℃.The results showed that the body weight gain and specific growth rate of the crab were foud to be increased gradually with the increasing feeding frequency,without significant differences( P 0.05).There were significantly higher survival and molting rates in the juveniles fed the formulated diets than those in the animals fed the fresh trash fish.Within the same feeding frequency,however,the crab fed the formulated diets had significantly higher food intake than the crab fed the fresh trash fish( P 0.05),and the food conversion efficiencies were decreased gradually in the different groups with increasing feeding frequency.The body composition of the crab was shown no significant differences in different groups with increasing feeding frequency( P 0.05),and there was no interaction between the diet types and feeding frequency on body composition of the crab( P 0.05).The crab fed the fresh trash fish showed gradual decrease in energy allocated to growth,and high metabolic energy with the increasing feeding frequency.However,the crab fed the formulated diets showed an opposite case.The partitions of fecal energy in growth energy were decreased gradually with the increasing feeding frequency in different groups.There was significantly higher fecal energy in the crab fed the formulated diets than that in the crab fed the fresh trash fish( P 0.05).In the experiment,the optimal feeding frequency was found at feeding frequency of twice a day.