effect of four medicinal plants with antibacterial property on immune system and ileal bacteria population of broilers

this experiment was conducted to investigate the effects of four medicinal plants with antibacterial property on immune system and ileum bacteria population of broiler chicks.a total 336 day-old male ross broiler chicks were used in a crd design with 6 treatments and 4 replicates per each treatment. cuminum l, mentha piperita l, achillea l, teucrium polium l, in levels of 1.5, 0.3, 0.2 and 0.2 percent, respectively. two treatments with and without antibiotic were considered as control groups. at the fifth week of experimental period, two birds were bled for investigating the immune system activity. also at the end of experiment, three birds from each pen were slaughtered to determine ileum bacteria population.medicinal plants had no significant effects on the antibody titer against newcastle disease virus, but heterophils increased significantly in birds fed diets containing achillea l. (p < 0.05). effect of antibiotic on enhancement of heterophils was significant. also, the usage of medicinal plants particularly mentha piperita l. diets significantly reduced clostridium concentration in ileum, (p<0.05). diets containing achillea l, and teucrium polium l reduced bifidobacterium. but control and antibiotic treatment increased bifidobacterium. results of this study have showed that various herbs have different effects on broiler system immune and ileal bacteria population. mentha piperita l and achillea l can be used to control clostridia infections in gastro intestinal tract and to support immune system in broiler chicks, respectivily.