Formulation and evaluation of diets for the African catfish, Clarias gariepinus (Burchell), made by partial replacement of fish meal with winged bean (Psophocarpus tetragonolobus L. DC) seed meal

(M)ature winged bean (Psophocarpus tetragonolobus L.) seeds (cultivar Tpt26) were subjected to different moist heat treatments (autoclaving, boiling, cooking, quick cooking), and the meals derived were assayed for protein content, trypsin-inhibitory activity, tannin content, lectin activity and in vitro digestibility. Quick-cooking treatment eliminated lectin activity, significantly reduced tannin content and trypsin-inhibitory activity, and improved in vitro protein digestibility. The quick-cooked winged bean meal was substituted for 20%, 40%, 60% or 80% of menhaden fish meal in dry production diets (400g of crude protein and 17.5MJ of gross energy kg(-1) dry diet) and fed to satiation to African catfish, Clarias gariepinus (Burchell), reared from fingerlings (15.4 +/- 1.6 g) to market size (> 300 g) over 240 days. Weight gain, growth rate, feed conversion, protein utilization and nutrient digestibility by catfish were not significantly different (P > 0.05), and their haematological characteristics were within the normal values reported in the literature. Carcass composition of catfish was not diet related, and liver composition did not indicate any lipid or glycogen accumulation, No significant differences were detected in sensory evaluation of catfish fillets. Feed costs were reduced by 25% when winged bean meal provided 50% of total dietary protein. Results show that winged bean meal is a suitable dietary protein source for the African catfish and represents an economic replacement for fish meal.