PROTEIN TO ENERGY RATIOS IN AFRICAN CATFISH FED PURIFIED DIETS: IS CLARIAS GARIEPINUS (BURCHELL) AN ORDINARY CARNIVORE?
Panagiotis A. Pantazis
Department of Agriculture, Animal Production and Aquatic Environment, University of Thessaly, Fytokou Street, Nea Ionia Magnisias, 384 46 Volos, Greece
ABSTRACT. Six diets made from purified and semi-purified materials (casein, gelatin, gluten, zein, dextrin, a-cellulose) were tested over an 80-day period in adult (150 ± 47.40 g) African catfish, Clarias gariepinus (Burchell). Six protein to lipid ratios were tested ranging from 12.85 mg protein kJ-1 to 20.51 mg protein kJ-1. Performance indices (PWG, SGR, FCR) compare favorably with those previously observed for C. gariepinus and other clariid species. The best performing diets were those with a total gross energy range of 22 to 24 kJ g-1, a P/E ratio of 19.5-20.5 mg protein kJ-1, a crude protein level of 46%, a crude lipid level of 10-17%, and a carbohydrate level of 26-32%. The carbohydrate levels (26-32%) of the best performing diets during these experiments were much higher than those of previous researchers (16-18%) for the same species and still higher than those (15-25%) employed for other carnivores (salmonids, sea bass, sea bream). Therefore, African catfish possibly exhibits more efficient dietary carbohydrate utilization. An increase in carcass lipid as a result of increased dietary non-protein energy was also recorded.
Key words: AFRICAN CATFISH (CLARIAS GARIEPINUS), CARBOHYDRATE UTILIZATION, CARCASS QUALITY, NUTRITION
Panagiotis A. Pantazis, University of Thessaly, Department of Agriculture, Animal Production and Aquatic Environment, Fytokou Street, Nea Ionia Magnisias, 384 46 Volos, Greece, Tel./Fax: (30) 421-93259, (30) 24210 93157;