To investigate the effects of Zataria multiflora Boiss essential oil (ZMB) on incidence of ascites syndrome and blood parameters of Arian broiler chicks, an experiment with 500 one-day-old chicks were conducted. This experiment was based on completely randomized design with 5 treatments including 1) control (basal diet), 2) basal diet with 100 mg/kg probiotic, 3) basal diet with 150 mg/kg avilamycine, 4) basal diet with 200 and 5) basal diet with 400 mg/kg Zataria multiflora Boiss essential oil) with 4 replicates and 25 chicks per replicate in a 42 days. At 35 days of age, 3 mL of blood was collected from the brachial vein of 2 birds from each pen. The concentrations of total protein, calcium, phosphorus, albumin, globulin, triglyceride, cholesterol, HDL and LDL in serum samples were subsequently measured. For investigating ascites related metabolites, hematocrits, RV/ TV ratio, heart weight, T3 and T4 hormones were measured.The RV/TV ratio was investigated at the age of 42 days According to result, using ZMB had no significant effect on blood parameters including, cholesterol, triglycerides, HDL, LDL, calcium, phosphorus, total protein, albumin, and globulin (p>0.05). Investigation of ascites related parameters indicated that red blood cells count, hematocrit, T3 and T4 hormones and heart weight didn’t affected by using ZMB (p<0.05). However, Zataria multiflora Boiss essential oil at levels of 200 and 400 mg/kg significantly reduced RV/TV ratio in comparison with control (p<0.05). As the RV/TV ratio is a reliable indicator for ascites, it can be concluded that Zataria multiflora Boiss essential oil could be attractive subject for future investigation in ascites induced broiler o-bid/_nu�E ��C ataria multiflora Boiss essential oil) with 4 replicates and 25 chicks per replicate in a 42 days. At 35 days of age, 3 mL of blood was collected from the brachial vein of 2 birds from each pen. The concentrations of total protein, calcium, phosphorus, albumin, globulin, triglyceride, cholesterol, HDL and LDL in serum samples were subsequently measured. For investigating ascites related metabolites, hematocrits, RV/ TV ratio, heart weight, T3 and T4 hormones were measured.The RV/TV ratio was investigated at the age of 42 days According to result, using ZMB had no significant effect on blood parameters including, cholesterol, triglycerides, HDL, LDL, calcium, phosphorus, total protein, albumin, and globulin (p>0.05). Investigation of ascites related parameters indicated that red blood cells count, hematocrit, T3 and T4 hormones and heart weight didn’t affected by using ZMB (p<0.05). However, Zataria multiflora Boiss essential oil at levels of 200 and 400 mg/kg significantly reduced RV/TV ratio in comparison with control (p<0.05). As the RV/TV ratio is a reliable indicator for ascites, it can be concluded that Zataria multiflora Boiss essential oil could be attractive subject for future investigation in ascites induced broiler |