Effects of Dietary Protein Levels and Energy to Protein Ratios on Growth and Protease Activity in Red Swamp Crayfish Procambarus clarkii

Juvenile red swamp crayfish Procambarus clarkii was fed the diets containing different protein levels and energy to protein ratios to evaluate the effects of the dietary protein levels and energy to protein ratios on growth and protease activity.The crayfish had the best growth performance when fed the diets containing 31.86% of protein and E/P level of 35.85 kJ/g.The protease activity in hepatopancreas and stomach increased significantly with the increase in dietary protein.There were no significant effects of E/P levels on the protease activity in intestine,hepatopancreas and stomach.The maximal protease activity was observed in the crayfish fed the diets containing 31.47% of protein and E/P level of 40.42 kJ/g.