Growth and Diet Utilization Efficiencies of Overwinter Juvenile Mud Crabs Fed with Different Diets

[Objectives] To study the utilization efficiency of different diets for juvenile Scylla paramamosain. [Methods] Low-value fish, shrimp, clam and clamworm were fed to overwintering young mud crabs, and the performance of the feed was evaluated by growth, feed utilization and energy allocation. [Results] Shrimp-fed mud crabs showed the best growth performance, while fish-fed mud crabs showed the worst growth performance and converted the least protein and energy for growth. Shrimp-fed mud crabs molted more frequently, and the dry matter mass and energy of Exuviation were significantly higher than those of fish-fed mud crabs. The shrimp-fed crabs also had significantly higher food intake than those fish-fed crabs. The order of feed conversion efficiency (FCE) of fish-fed mud crabs was Polychaete>clam>shrimp>fish, while the order of FCE calculated with FCE-P and FCE-E was Polychaete>clam>shrimp>fish. Fish-fed mud crabs had the least energy intake and the least energy for growth, molting, excretion, metabolism, and feces. Among the four treatments, the mud crabs fed on Polychaete had the largest proportion of energy used for growth, while the mud crabs fed on fish had the largest proportion of energy used for molting. The proportion of energy consumed by mud crabs fed on Polychaete was the smallest, which may be the main reason for the higher FCE-P and FCE-E of mud crabs fed on Polychaete. [Conclusions] The results of this experiment showed that the utilization of low-value fish by mud crabs was the worst, suggesting that fish should not be used as control or reference food when studying the formula feed of mud crabs.