The present study was conducted on 320, one-day old commercial straight run broiler chicks for a period of six weeks. The birds were randomly divided into eight treatment groups i.e. A, B, C, D, E, F, G and H comprising of 40 birds in each treatment with two replications of 20 birds in each replicate. Treatment group A served as control. Treatment group B was control with β-mannanase enzyme. Guar meal through feed was incorporated @ 5%, 10%, 15% with β-mannanase 5g, 10g and 15g /100 kg of feed to D, F, H Treatment groups. However plain GM was incorporated through feed to treatment groups C, E and G @ 5, 10, and 15 percent respectively. There were significant differences (P<0.05) observed for weekly gain in weight, weekly feed consumption and weekly feed conversion ratio when the diet was supplemented with β-mannanase enzyme up to 5 percent level of incorporation of GM. Body weights at 6thweek were 2031, 2218, 1946, 2112, 1768.50, 1849.50, 1663.50 and 1726g for treatment groups A, B, C, D, E, F, G and H respectively. The cumulative weight gain at 6th week were 1986, 2173.50, 1901, 2067, 1723.50, 1804.50, 1618.50 and 1681 g for treatment groups A, B, C, D, E, F, G and H respectively. The Cumulative feed consumption exhibited significant differences (P<0.05) at 6th week. The feed consumption at the end of 6th week was 3422, 3623.50, 3318.50, 3500, 3278, 3334.50, 3264.50, and 3290 g for treatment groups A, B, C, D, E, F, G and H, respectively. The cumulative feed conversion ratio also revealed significant findings at the end of 6th week. The FCR was 1.72, 1.66, 1.74, 1.69, 1.90, 1.84, 2.01 and 1.95 for the A, B, C, D, E, F, G and H, respectively. The total cost of broiler production was Rs. 131.62, 136.97, 131.76, 137.15, 133.66, 135.65, 133.86 and 135.24 for treatment groups A, B, C, D, E, F, G, and H, respectively. The net profit per bird was highest for Treatment group B (Rs.36.07), followed by D (Rs.27.58), A (Rs.26.79), C (Rs.20.02), F (Rs.8.61), E (4.28), H (-0.61) and G (Rs.-4.11). However profit per bird was more in the control group supplemented with β- mannanase enzyme @ 5 g /100 kg of feed followed by GM supplemented @ 5 % with β- mannanase enzyme @ 5 g /100 kg of feed. The results of the present study clearly inferred that lower level i.e. @5 % replacement of soya Doc with toasted guar meal had exhibited beneficial effects with respect to BWG,FCR and economics of broiler production with supplementation of β- mannanase enzyme. It can be further be concluded that addition of toasted guar meal above 10 and 15% cannot work as a potential tool for partial replacement of soya Doc in poultry diet even after the supplementation of β- mannanase enzyme because of adverse effect of guar meal on broiler performance.