Effect of peppermint, thyme and tarragon essential oils on the performance and antibody titer in broilers

This research was carried out in order to investigate the effect of peppermint, thyme and tarragon essential oils on the performance and antibody titer of broilers. In this experiment, a total number of 240 Cobb 500 broiler chickens were used in a completely randomized design with eight treatment groups. Each treatment was replicated five times with six birds per replicate. Dietary treatments included; control, 200 mg/kg virginiamycin antibiotic, 150 and 200 mg/kg peppermint, thyme and tarragon essential oils. Chickens fed diets supplemented with antibiotic and 200 mg/kg thyme essential oil had significantly higher daily weight gain in comparison to control diet at the period of 21-42 days and 1- 42 days. Feed conversion ratio in birds fed the diets supplemented with 200 mg/kg peppermint essential oil and antibiotic was significantly improved in comparison to control diet. The highest ileum length and the best antibody titer against bronchitis and Gumboro in 42 days old chickens were recorded in150 mg/kg tarragon essential oil, 200 and 150 mg/kg peppermint essential oils, respectively. Therefore, it is recommended to supplement 200 mg/kg peppermint or thyme essential oils instead of dietary antibiotics in order to improve performance and antibody titer in broilers.