An Evaluation of Diets Containing Various Levels of Fermented Cottonseed Hull on Digestibility and Growth of Nile Tilapia (Oreochromis niloticus) Fingerlings

Cotton seed hull, a by-product of cotton seed oil industry, was fermented and evaluated as an ingredient in practical diets for Nile tilapia (Oreochromis niloticus) fingerlings reared in hapas suspended in an outdoor concrete cistern. Fermentation resulted in the reduction of condensed tannin and crude fibre levels and an elevation of the crude protein content. Five isonitrogenous (30% crude protein) and isocaloric (19.50 KJg^-1) diets were formulated in which maize meal was progressively substituted at four inclusion levels (15, 30, 45 and 60%) with fermented cottonseed hull. The fish were fed for eight weeks. Results showed a progressive decline in growth performance with an increase in the inclusion level of cottonseed hull. The data showed significant difference (p 0.05) in weight gain, specific growth rate and feed conversion ratio among fingerlings fed the different dietary treatments. Result of carcass analysis showed that as the inclusion level of fermented cottonseed hull increased, there was a progressive decrease in body lipid while other carcass parameters did not show any set pattern. It was concluded that cottonseed hull was suitable as a dietary energy supplement for tilapia (O. niloticus) fingerlings when incorporated only up to 15% replacement for maize meal. It is suggested, however, that further studies be carried out to reduce the anti-nutritional content of this resource.