NUTRITIVE-VALUE OF DRIED LACTIC-ACID FERMENTED FISH SILAGE AND SOYBEAN-MEAL IN DRY DIETS FOR JUVENILE CATFISH, CLARIAS-GARIEPINUS (BURCHELL, 1822)

Dry diets containing either fish meal (C-FM) or dried fermented fish s ilage and soybean meal blend (1:1,ww(-1)) (C-FS) as the sole protein s ource, were fed to triplicate groups of juvenile Clarias gariepinus (1 0.8 +/- 0.3 g) at 5% body weight per day for 70 days. Catfish fed the C-FS diet showed reduced (P < 0.05) growth rate, feed conversion, prot ein efficiency and digestibility. Lower amounts of available amino aci ds in the C-FS diet resulted in inferior nutritive value for catfish g rowth than in the C-FM diet. Postprandial changes in plasma amino acid s showed similar patterns in both diet treatments, but the maximal mea n levels attained for the C-FS diet were correspondingly lower and occ urred earlier than with the C-FM diet. There were no effects of feedin g C-FS diet on the hepatosomatic index but carcass analysis showed tha t body protein deposition was lower (P < 0.05). Differences in haemato crit, haemoglobin content and liver histology were demonstrated but we re not pathological. Lower digestible energy of C-FS diet also contrib uted to the poor performance of catfish in this treatment. Results of this study indicate that C. gariepinus cannot metabolize protein from co-dried fish silage as efficiently as fish meal protein when used as the sole dietary protein.