It has been well established that some wheat cultivar contained higher level of soluble non-starch polysaccharides which may adversely influence broiler chicks’ performance, especially when wheat inclusion level in the diet exceed birds’ tolerance level. An experiment was carried out using 3 common wheat varieties popular in Kurdistan region, Iran (known as Sardari, Zarrin and Azar) with or without enzyme preparation (0.30 g / kg of diet, Grindzyme GP 15000) on performance of broiler chicks during 1 to 42 d of age. A total of 416, one day old Ross 308 broiler chicks were randomly assigned to 8 dietary treatments, each replicated 4 times (in floor pen) in a completely randomized design (CRD) with 4 × 2 factorial arrangements. Wheat inclusion level in wheat-SBM based diets during starter and grower period was set at 62.05 and 66.47%, respectively. Corn-SBM based diet (with or without enzyme supplementation) set as control treatments. Chick’s body weight, feed intake and feed conversion ratio, after mortality adjustments, were determined in weekly intervals. At ages of 20 and 40d, 4 birds per treatment were sampled for measurement of relative weight of gastrointestinal organs and carcasses characteristics. Results showed that birds fed corn-SBM basal diet had significantly (P < 0.05) higher feed intake during 1–21d, body weight at 21d, and daily gain during 1–21d compared with birds fed with wheat-SBM based diets; however, the difference among corn and wheat based treatments disappeared during 21–42d. The results also indicated that wheat cultivar did have significant (P < 0.05) impacts on birds’ feed intake, feed conversion ratio and relative weight of different gastrointestinal organs. Results showed that addition of enzyme to the diet did not have significant (P > 0.05) influence on birds body weight; however, enzyme supplementation significantly (P < 0.05) improved feed conversion ratio and increased ileum relative weight (%). In conclusion, the results showed the
