This study was conducted to investigate the effect of replacing soy bean meal (SBM) by cottonseed meal (CSM) with or without of protease enzymes, on performance, in-vitro protein digestibility, carcass characteristics, gastrointestinal morphology and hematological parameters in broilers. A total 450 one-day-old mixed sex broiler chickens Ross 308 were managed in 6 treatments, 5 replicates and 15 chickens in each in a 2 × 3 factorial arrangement with completely randomized design (CRD). Treatments consist of: treatment 1 (0% CSM, -protease), treatment 2 (0% CSM, +protease), treatment 3 (20% CSM, -protease), treatment 4 (20% CSM, +protease), treatment 5 (30% CSM, -protease), treatment 6 (30% CSM, +protease). The results have shown that there were no significant affected on feed intake, body weight gain and feed conversion ratio by various treatments in starter period (P>0.05). Digestive organs and body weight were not affected by treatments at 27 days of age. Breasts weight was significantly increased by 20% replacement SBM with CSM (P<0.05). Protein digestibility was increased significantly by protease enzymes and in vitro method. Serum cholesterol levels reduced by enhanced levels of replacement CSM (P<0.05). There was concluded that no adverse effects were found by replacing 30% SBM with CSM on performance status, as well as improved in vitro protein digestibility. تفاصيل المقالة