The experiment was carried out at Bangabandhu Sheikh Mujibur Rahman Agricultural University Poultry Farm, Salna, Gazipur, Bangladesh. Two hundred fifty-two (252) healthy day-old Cobb-500 broiler chicks were weighed and randomly allocated to six dietary treatments replicated three times with fourteen birds per replicate in a Complete Randomized Design (CRD).The dietary treatments were: T0, SBM based diet; T1, 10% CSM protein with 90% SBM protein; T2, 20% CSM protein with 80% SBM protein; T3, 30% CSM protein with 70% SBM protein; T4, 40% CSM protein with 60% SBM protein and T5, 50% CSM protein with 50% SBM protein. A strict bio-security program was maintained inside and outside of the research shed. The birds were vaccinated against Infectious Bursal Disease (IBD) and Newcastle Disease (ND). The management practices were identical for all dietary groups. Electric light was provided for 23.5 hours and the brooding temperature was almost maintained at 33±2°C for the first week. In course of the trial, the temperature was gradually reduced to 25±2°C at the end of the experiment. Fresh and dried sawdust was used at a depth of about 3 cm for bedding material. The birds were critically observed twice a day for clinical signs if any (slow movement, infrequent sitting, lack of appetite, significant changes of feathering, paralysis, etc.) and for monitoring other activities. Feeders were cleaned each week and drinkers were washed twice daily. The experimental diets were formulated by replacing soybean meal with CSM according to the recommendation of NRC  in three phases namely starter (1 to 14 days), grower (15 to 28 days), and finisher (29 to 35 days). All feed ingredients were weighed separately and soyabean oil was incorporated into soybean meal first and then mixed thoroughly with other macro ingredients. Micro ingredients were mixed thoroughly with the ground maize and then mixed with the other macro ingredients. Diet for each treatment was prepared properly as per recommendation. All diets were free from antibiotics. The broiler mash feed was supplied three times daily on an ad libitum basis. On the 35th day of the experiment, three (3) birds from each replicate were randomly selected from each pen and each broiler chicken was weighed. Birds were sacrificed and hanged until complete bleeding. After complete bleeding, the birds' feathers were removed by hand, and pining was done manually. Viscera and giblet were removed from the carcass. Legs, head, neck, and shank were separated from the body parts. Live bird, slaughtered bird (after complete bleeding), skin, viscera, giblet, legs, head, neck, shank, and carcass were weighed individually. Breast muscles were collected randomly from each replicate. The feed intake of each replication was determined by subtracting the amount of leftover from the amount of supplied feed on the previous day. The live weight of each bird was recorded as the average weight of all birds of each replicate. Carcass weight and dressing percent were calculated accordingly by considering the live weight of broilers for each replication. Samples of breast meat were analyzed to determine the dry matter (DM), crude protein (CP), ether extract (EE), crude fiber (CF), nitrogen-free extract (NFE), and total ash according to the methods of the Association of Official Analytical Chemists. The data were analyzed by using the statistical program (SPSS 16.0) to compute analysis of variance (ANOVA) for a completely randomized design (CRD) and Duncan’s multiple range test (DMRT) was done to differentiate among the treatment means at a 5% level of significance.