It is concluded from the present study, that replacing SBM with guar korma at the rate of 20 g/kg in the pre-starter and 50 g/kg in starter and finisher diets with or without β-mannanase supplementation resulted in poorer feed conversion and inferior performance index score. Plausibly, the residual indigestible polysaccharides, such as pectin and β-galactomannan present in the guar korma increased the intestinal viscosity and inhibited the performance of broilers. In summary guar korma as a replacement for SBM at the levels tested in this study may not be beneficial under practical conditions and that further research is warranted to determine a more accurate level of inclusion of guar korma for better performance and carcass yields of birds.