EFFECTS OF PROTEIN LEVEL IN ISOCALORIC DIETS ON GROWTH-PERFORMANCE OFTHE JUVENILE CHINESE HAIRY CRAB, ERIOCHEIR-SINENSIS

A feeding trial was conducted in a semi-recirculating water system to investigate the effects of the dietary protein level in isocaloric die ts on growth performance of juvenile Chinese hairy crabs, Eriocheir si nensis, Six shrimp meal based diets, which contained various protein l evels (29.8 to 54.8%) with the digestible energy of 3.47 to 3.55 kcal/ g dry matter, were formulated and fed to crabs for 35 days. The diet c ontaining 39.0% dietary protein produced the best values in weight gai n (WG), specific growth rate of body weight (SGRw), feed conversion (F C), protein efficiency ratio (PER) and body protein gain (BPG), Crabs fed the 39.0% protein diet had significantly higher WG than those fed the 29.8 and 34.1% protein diets. There were no significant difference s in WG, SGRw, FC, PER and BPG values among crabs fed the 44,2, 48.7 a nd 54.8% protein diets. The PER and apparent protein utilization (APU) of crabs fed diets with 29.8, 34.1 and 39.0% dietary protein were sig nificantly higher than those of crabs fed higher dietary protein. The protein level for maximal growth was estimated to be 42.5%, Body prote in content was not significantly affected by the dietary protein level . The contents of body lipid and carbohydrate tended to decrease as th e dietary protein level increased. These results indicate that the opt imum dietary protein level ranges from 39.0 to 42.5% for juvenile E. s inensis. (C) 1998 Elsevier Science B.V. All rights reserved.