EFFECTS OF FEEDING THE REPARTITIONING AGENT L644,969 ON GROWTH AND BODY-COMPOSITION OF BLUE CATFISH, ICTALURUS-FURCATUS, FED DIETS CONTAINING 2 PROTEIN-LEVELS REARED IN CAGES

Juvenile blue catfish with an average initial weight of 110 g, were st ocked into 3.5-m(3) floating cages at a rate of 200 fish/cage and fed one of four diets. Diets contained either 27 or 36% protein and either 0 or 3 mg/kg of the beta-adrenergic agonist (BAA) L644,969. There wer e three replicates per diet. Fish were fed all they would consume in 4 0 min for 94 days. There was no significant effect of protein, L644,96 9, or their interaction (P > 0.05) on final individual weight, percent age weight gain, survival, and specific growth rate (SGR). No differen ce (P > 0.05) in whole body composition was found between protein leve ls; however, fish fed diets containing L644,969 had a higher (P < 0.05 ) fillet dressout and a lower (P < 0.05) percentage of abdominal fat t han fish fed control diets. The fish fed 3 mg L644,969/kg diet had 15% more protein and 28% less lipid in the fillet than fish fed control d iets (P < 0.05). Fish fed diets containing L644,969 also had a signifi cantly higher (P < 0.05) percentage of protein and a lower percentage of lipid in viscera than fish fed diets without the BAA. These results indicate that blue catfish reared to 485 g in cages can be fed as muc h as they will consume of a diet containing 27% protein without advers ely affecting growth, and that the addition of 3 mg L644,969/kg to die t containing either 27 or 36% protein reduces lipid deposition in musc le and visceral depots while increasing protein accretion in muscle.