Asian Journal of Research in Agriculture and Forestry

Soyabean meal (SBM) could be a suitable replacement for the expensive fishmeal but for its low digestibility in fish. However, protease supplementation could improve digestibility of SBM based diets. Therefore, apparent and true digestibility in Clarias gariepinus fed SBM based diets supplemented with protease were investigated. Six diets containing varied inclusion levels of protease (ppm) in solvent extracted soybean-based diets (SESBD) were formulated; Control (without protease), SS₁₀₀ (100), SS₂₀₀ (200), SS₃₀₀ (300), SS₄₀₀ (400), SS₅₀₀ (500). The Clarias gariepinus (n=720) weighing 12.00±0.10g were fed to satiation with the diets for 12 weeks. Each treatment was in triplicate. Protease supplementation significantly (P<0.05) influenced the weight gain of C. gariepinus with the higher value in fish fed SS400 (44.63±3.13) and least value in control diet (32.03±0.65).  FCR had a significantly (P<0.05) least value in C. gariepinus fed SS400 (1.62±0.18) but similar (P>0.05) to C. gariepinus diet SS300 (1.88±0.11). Supplemental protease in soyabean-based diet improved (P<0.05) apparent protein digestibility of C. gariepinus on diet SS400 (87.38±1.10) but similar (P>0.05) to C. gariepinus on diet SS200 (87.29±0.97). Also, true lysine digestibility was enhanced with protease supplementation in soybean-based diet with the higher value in diet SS200 (95.90±0.07). Optimal FCR occurred SESBD of 350ppm dietary inclusion (R²= 0.8147) of protease.  The findings suggest that, protease supplementation in solvent extracted soyabean based diet could improve growth performance and amino acid digestibility in C. gariepinus at 350ppm inclusion level.