Nutritional evaluation of toasted Mucuna utilis seed meal and its utilization in the diet of Clarias gariepinus (Burchell, 1822)

The value of toasted Mucuna utilis seed meals was investigated in this study by evaluating the nutritional profile and the utilization of the processed seeds in isonitrogenous (35% CP) and isocaloric diets (17 kJ g?1) for African catfish Clarias gariepinus (Burchell 1822). Toasting the M. utilis seed significantly reduced the levels of tannins, phytate, trypsin, and hemagglutinin in the seeds. However, protein, gross energy, arginine, histidine, and valine were increased (P ≤ 0.05). The processed seed was then used to formulate five experimental diets by progressively increasing its inclusion (by 50 g kg?1) from zero up to 200 g kg?1. A sixth diet was also formulated with raw M. utilis included at 200 g kg?1 to determine the efficacy of the processing method applied in this study. Fifty fingerlings of C. gariepinus (2.02 g ± 0.08) stocked in 18 hapas measuring 1 × 1 × 1 m³ were then fed the diets for 56 days. The growth of C. gariepinus fingerlings was significantly improved by the addition of the toasted M. utilis seed meal. However, fish fed the diet containing 200 g kg?1 of raw M. utilis had poor growth with higher mortality (35%). Estimation of the feeding cost using the diets revealed reduction in production cost of fish with the inclusion of toasted M. utilis seed meal. It was concluded that toasting significantly improved the nutritional quality of this unconventional feedstuff, allowing better utilization at up to 200 g kg?1 inclusion level in the diet of African catfish C. gariepinus.