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Fish-silage (FS), prepared from lactic acid fermentation of whole tilapias, 5% sugar beet molasses and 2% Lactobacillus plantarum, was blended and co-dried with soybean meal (SBM), poultry by-product meal (PBM), hydrolysed feather meal (HFM) and meat and bone meal (MBM). The blends were evaluated as protein source (providing 50% of dietary protein) in dry diets (40% protein, 4·3 kcal g−1 gross energy) for juvenile catfish, Clarias gariepinus, fed at 4% body weight day−1 for 70 days. The fish-silage pellets maintained their shape during water immersion and their water stability was high and similar (P>0·05) to that of a reference diet. Clarias gariepinus fed on the different fish-silage diets showed some significant (P 0·05). Protein digestibility was reduced (P

Fermented fish-silage was prepared from whole tilapias, 15% molasses and 5% Lactobacillus plantarum starter culture and used as protein supplement in moist diets for juvenile catfish, Clarias gariepinus. Carboxymethyl cellulose, guar gum or wheat gluten was incorporated as alternative binder into diets at 2% and their effects on water stability and nutrient leaching were determined. The pellets maintained a high water stability regardless of the binder used, and losses of total nitrogen were low (

Fermented fish silage was produced from minced tilapia ( Oreochromis niloticus ), 15% molasses and 5% Lactobacillus plantarum culture. Initially, batches of the fish silages were fermented at 5, 20, 30 or 35°C for 30 days. The pH declined rapidly at 20, 30 and 35°C but at 5°C, pH decline was slower. Protein solubilization (autolysis) in the fish silages was temperature-dependent as the non-protein nitrogen content (NPN) increased rapidly at higher temperatures. In a second experiment, fish silage was fermented at 30°C for 7 days after which autolysis was halted, then stored at 30°C for 180 days and analysed at intervals. The NPN attained a maximum of 51·4% of total nitrogen content after 180 days. Proximate composition of tilapia silages varied slightly during storage and there was a slight loss of tryptophan during fermentation and storage. The stored wet tilapia silages were blended with soybean meal (1:1, w/w) and dried. The nutritional value of co-dried tilapia silage as a dietary protein supplement for catfish ( Clarias gariepinus ) was studied in digestibility experiments. Although the protein quality of wet tilapia silage was reduced during storage, there were no differences ( P > 0·05) in the apparent protein digestibility coefficients of diets containing co-dried tilapia silages. It is suggested that autolysis in the stored tilapia silages had little effect on proten digestibility in the catfish.

Feeding and digestibility studies were conducted in concrete ponds to evaluate the use of coffee (Coffea robusta) pulp as partial and total replacements for yellow maize in low-cost diets for the catfish, Clarias isheriensis (Sydenham, 1980). The percentages of dietary coffee pulp inclusion were 0 (diet 1, control), 10 (diet 2), 20 (diet 3) and 30 (diet 4). All the diets were formulated to contain 37% crude protein using cheap, locally available feed ingredients, and fed daily to experimental fish in replicated dietary treatments at 2–10% of fish biomass for 150 days. Fish survival was high, consequent upon good water quality in all treatments. There were significant differences (P

Trials on growth performance, nutrient utilization and digestibility, as well as carcass composition, were conducted on the clariid catfish, Clarias isheriensis (Sydenham, 1980) to evaluate the replacement value of peels of cassava, yam and plantain, and maize chaff, as substitutes for maize in low-cost fish diets. Triplicate groups of C. isheriensi fingerlings (mean weight, 34·72 g) were fed for 84 days with 37% crude-protein diets containing each of the energy substitutes at 25% inclusion level. The maize chaff diet produced the greatest body weight increases and best growth performance as well as the best feed utilization. This was followed by yam peel, plantain peel and cassava peel diets in decreasing order. Apparent nutrient digestibility coefficients of the experimental diets followed a similar trend. Only the maize chaff diet compared favourably with the control (yellow maize) diet with regard to nutrient utilization and digestibility, which indicated that maize chaff had the greatest potential and desirability as a replacement for yellow maize as the energy source in low-cost diets for C. isheriensis.