CHEMICAL AND NUTRITIONAL QUALITY OF STORED FERMENTED FISH (TILAPIA) SILAGE

Fermented fish silage was produced from minced tilapia (Oreochromis ni loticus), 15% molasses and 5% Lactobacillus plantarum culture. Initial ly, batches of the fish silages were fermented at 5, 20, 30 or 35-degr ees-C for 30 days. The pH declined rapidly at 20, 30 and 35-degrees-C but at 5-degrees-C, pH decline was slower. Protein solubilization (aut olysis) in the fish silages was temperature-dependent as the non-prote in nitrogen content (NPN) increased rapidly at higher temperatures. In a second experiment, fish silage was fermented at 30-degrees-C for 7 days after which autolysis was halted, then stored at 30-degrees-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 til apia silages were blended with soybean meal (1:1, w/w) and dried. The nutritional value of co-dried tilapia silage as a dietary protein supp lement for catfish (Clarias gariepinus) was studied in digestibility e xperiments. Although the protein quality of wet tilapia silage was red uced during storage, there were no differences (P > 0.05) in the appar ent protein digestibility coefficients of diets containing co-dried ti lapia silages. It is suggested that autolysis in the stored tilapia si lages had little effect on protein digestibility in the catfish.