effects od oregano oil, probiotic and antibiotic on performance, immune response in broiler

to evaluate the effect of essential oils of oregano on performance, immune response in broiler chickens arian, an experiment in a completely randomized design with a total of 500 broiler chicks, in 5 treatments, including the control diet, control diet + 100 mg/kg protexin, control diet + 150 mg/kg avilamysine and control diet + 200 and 400 mg/kg oregano oil with 4 replicates and 25 chicks were used. at age 42 days, from each experimental group randomly selected birds and to investigate performance parameter and ascites were slaughtered. at 35 days of age, to investigate the humeral immune response, the immune response against sheep red blood cells (srbc) and blood factors, three birds of each treatment selected and from them were taken blood sample through vein under the wing. body weight, feed conversion rate, feed intake, survival and production index in 42 days of age was not affected by treatment (p>0.05). heterophile percent in treatment 200 mg / kg oregano highest value (30.20) and no significant differences (p=0.062) with treatments 400 mg/kg oregano and control group (respectively 27.00 and 26.80). no significant differences (p>0.05) in the percentage of lymphocytes was observed between the different treatments.heterophil to lymphocyte ratio (h/l) in the group containing 200 mg/kg oregano highest value (0.449) and a significant difference (p=0.077) with a 400 mg/kg oregano and control group (respectively, 0.385 and 0.381). none of the treatments showed no significant effect on antibody titer against srbc (p>0.05). the results indicate oregano on cellular immunity in broilers.