Effect of feeding cooked-extruded diets, containing different levels of protein, lipid and carbohydrate on growth of red swamp crayfish (Procambarus clarkii)

Two nutritional trials were conducted with juvenile red swamp crayfish Procambarus clarkii using eight cooked-extruded diets containing different levels of protein, lipid and carbohydrate: H20 (22/5/41), H25 (26/6/36), H30 (30/6/33), H35 (35/6/28), G25 (25/14/21), G30 (32/11/21), G35 (35/8/24), G40 (41, 6, 22), respectively. In the first experiment, crayfish were kept in individual containers and all diets were given for a period of 165 days. In general, lower lipid diets led to better growth and survival, protein levels of 22, 26 and 30% protein were adequate. After 105 days mortality decreased and weight remained stable for animals fed most diets, except for those containing 22% protein which increased. A good final weight was also obtained with diets containing 22, 26 and 30% crude protein. In the second trial, only diets H20, H25 and H30 were used. Crayfish were stocked in collective tanks and fed the test diets for 150 days. Growth was better than in the previous experiment, and the three diets gave similar final liveweights, survival and total weight. In summary, the optimum nutrient levels for red swamp crayfish growth under our experimental conditions were 22-26% crude protein, 6% lipid and 36-41% carbohydrate, with 10-12 MJ/kg (2.4-2.9 Mcal/kg) of energy content and 17-21 g/MJ (4.1-5.0 mg/kcal) of protein/energy ratio. (C) 1999 Elsevier Science B.V. All rights reserved.