CHEMICAL AND NUTRITIONAL QUALITY OF FERMENTED FISH SILAGE CONTAINING POTATO EXTRACTS, FORMALIN OR GINGER EXTRACTS

Fermented fish silages were prepared from whole tilapia (Oreochromis n iloticus), 15% molasses and 5% Lactobacillus plantarum starter culture . After fermentation for 72 h, potato extracts (PE), formalin or ginge r extracts (GE) were added at 5 ml/kg silage as proteolytic inhibitor or lipid antioxidant, and incubated at 30 degrees C for 30 days. The e ffects of presence or absence of these additives on various protein an d lipid quality parameters were periodically examined. PE had a slight and insignificant effect on protein solubilization and proteolytic ac tivity; hence it was not effective as a proteolytic inhibitor. Formali n prevented further hydrolysis of protein and reduced ammonia producti on. GE proved effective as an antioxidant in fermented tilapia silage, as the thiobarbituric acid value remained low after 30 days' incubati on. The tilapia silages were incorporated into dry tilapia diets and t he digestibility of nutrients determined. The formalin-treated tilapia silage diet gave significantly reduced (P < 0.5) digestibility of dry matter, nitrogen or lipid compared to the control, PE-treated or GE-t reated silage diets.