Evaluation of Fermented Agricultural By-Products as Dietary Substitutes for Conventional Feedstuffs in Tilapia Production in Nigeria

This study evaluates fermented agricultural by-products as substitutes for conventional feed ingredients in the diet of Nile tilapia (Oreochromis niloticus) in Nigeria, assessing growth performance, nutrient utilisation, gut histology, and cost-effectiveness. Tilapia production is expanding rapidly in Nigerian freshwater aquaculture, but feed cost representing 60 to 70 percent of production expenses remains the primary profitability constraint. Fermentation of locally available agricultural by-products including cassava peels, sorghum husk, and brewery waste can improve their nutritional value and digestibility for fish. This study uses a completely randomised design testing five dietary treatments in which 25 and 50 percent of the conventional feed protein fraction (soybean meal plus fishmeal) is replaced by fermented cassava peel protein and fermented sorghum husk protein, using a factorial combination design. Three hundred tilapia juveniles averaging 8.6 grams initial weight are stocked in 15 fibreglass tanks of 20 fish each. Growth parameters, feed conversion ratio, protein efficiency ratio, apparent digestibility coefficients, intestinal morphology, and feed cost per kilogram weight gain are measured over 56 days at University of Agriculture Makurdi aquaculture research facility. Findings reveal that 25 percent replacement with fermented cassava peel significantly reduces feed cost by 28 percent while maintaining growth performance equivalent to the conventional control diet. Digestibility of fermented by-products is significantly higher than unfermented equivalents. Intestinal villus height is not significantly different from control treatments at 25 percent inclusion. The study contributes original fermented by-product utilisation data for Nigerian tilapia production and recommends a scaled commercialisation pathway for fermented agricultural by-product fish feed production.

Keywords: tilapia, fermented by-products, feed cost, Nigeria, aquaculture nutrition.