Fagbenro, O., Oresegun, A., Nwanna, L., Ilona, P., Olurotimi, O. and Adebayo, A.

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Cassava (cultivar TME419) leaves were processed into leaf protein concentrate and evaluated in diets (320 g/kg protein, 80 g/kg lipid, 19.5 MJ/kg gross energy) fed to Oreochromis niloticus (3.2±0.3 g) and Tilapia zillii (3.3±0.4 g). A control diet (TD1) contained solvent-extracted soybean meal (SBM), which was substituted at 20%, 40%, 60% or 80% with the cassava leaf protein concentrate (CLPC) in test diets TD2, TD3, TD4 or TD5, respectively. Fishes were assigned in triplicate diet treatments (60 fish/treatment) in a complete randomized design (60 fish/treatment) and fed to apparent satiation twice daily for 70 days. Data were analysed statistically using one-way analysis of variance test. No fish mortality occurred in all treatments. Values obtained for growth response indices (mean weight gain, percentage weight gain) were statistically similar (p >0.05) as CLPC substituted up to 60% and 80% of SBM in diets for O. niloticus and T. zillii, respectively, and there were good growth response and diet utilization. Fish growth declined and diet was poorly utilized beyond 60% or 80% these inclusion levels, caused by reduction in protein and energy digestibility. O. niloticus fed with diet TD5 showed slight histological alterations in livers; caused by residual anti-nutrients while T. zillii showed no alterations or abnormalities. Erythrocyte sedimentation rate was significantly higher (p <0.05) in O. niloticus fed with diet TD5, while haematocrit, haemoglobin concentration, erythrocyte and leucocyte counts were statistically similar (p >0.05). The suitability of CLPC as dietary protein for O. niloticus will depend on further reduction/removal of inherent anti-nutrients as well as improving digestibility of nutrients. Key words: Cassava leaf protein concentrate, protein source, soybean replacer, tilapia diets