Fermentation of hydrothermal processed Jatropha curcas Kernel: Effects on the performance of Clarias gariepinus (Burchell, 1822) fingerlings

•Boiling and fermentation improved nutritional value of Jatropha curcas kennels.•Dietary inclusions of co-processed J. curcas improved growth of Clarias gariepinus.•Blood parameters were better with dietary inclusions of co-processed J. curcas. Anti-nutritional factors can be substantially reduced with processing to increase the utilization of feed ingredients. In this study, hydrothermally processed Jatropha curcas kernel (JCK) (62 min) was subjected to a natural un-inoculated fermentation process for varying durations (7, 14 and 21 days) to improve their nutritional profile and utilization by African catfish Clarias gariepinus (Burchell, 1822). Two control groups were also tested alongside; namely raw and hydrothermally processed JCK (without fermentation); hence making a total of five treatments for this study. The result obtained showed that fermentation improved the nutritional characteristics of the JCK compared to both controls. More so, prolonged duration of fermentation tends to positively affect the feed ingredient by increasing protein and fat content and substantially reducing anti-nutritional factors. Feeding trial conducted for 56 days with five formulated isonitrogenous (35 % CP) and isocaloric (315 kcal g−1) diets showed that C. gariepinus performed better with dietary inclusion of JCK meal co-treated hydrothermally and fermented. A similar trend was also observed with haematological parameters suggesting that the inclusion of the hydrothermally/fermented JCK meal improved the health status of the fish. However, carcass protein was similar regardless of the duration of fermentation but better than both control groups. It was therefore concluded that combined treatment of hydrothermal processing and fermentation improved the nutritional profile of JCK and its dietary utilization in the diet of African catfish fingerlings.