GROWTH AND PROTEIN-UTILIZATION BY JUVENILE CATFISH (CLARIAS-GARIEPINUS) FED MOIST DIETS CONTAINING AUTOLYSED PROTEIN FROM STORED LACTIC-ACID-FERMENTED FISH-SILAGE

Fermented fish -silage was prepared from whole tilapias, 15% molasses and 5% Lactobacillus plantarum starter culture and used as protein sup plement in moist diets for juvenile catfish, Clarias gariepinus. Carbo xymethyl cellulose, guar gum or wheat gluten was incorporated as alter native binder into diets at 2% and their effects on water stability an d nutrient leaching were. determined. The pellets maintained a high wa ter stability regardless of the binder used, and losses of total nitro gen were low (< 8%) on a per gram diet recovered basis. Apparent diges tibility coefficients for dry matter, nitrogen or lipid in the diets w ere high and similar when carboxymethyl cellulose or wheat gluten was used as the binder; but were reduced (P < 0.05) with guar gum. C. gari epinus (mean weight, 18.5 +/- 1.3 g) were fed silage diets at 5% of bo dy weight/day, twice daily, for 70 days in a recirculated water system with water temperature maintained at 27-degrees-C. Growth was better or similar when some of the protein was supplied by silage stored for 15 or 30 days, respectively. Differences in growth and protein utiliza tion were demonstrated, but there were no effects on body (fillet) com position. The results showed that incorporation of autolysed protein i n fish diets did not reduce dietary quality of feed for C. gariepinus. No morphological deformities were observed It is concluded that ferme nted silage stored for 15 days is beneficial as protein supplement in aquafeeds.