thyme (thymus vulgaris l.) and oregano (oreganum vulgare l.) essential oils for broilers: effect on performance, antioxidant indices and blood biochemical parameters

this study was conducted in order to evaluate the effect of thyme (thymus vulgaris l.) and oregano (oreganum vulgare l.) essential oils on performance, carcass characteristics, antioxidant status and blood biochemical parameters in broiler chickens. a total of 216 as-hatched broilers (ross-308) were divided into 6 treatments with 3 replications of 12 birds per each. experimental treatments were as follow: control group without additive, positive control group with 200 parts per million (ppm) vitamin e , diets containing 200 and 400 ppm of thyme essential oil and diets containing 200 and 400 ppm of oregano essential oil. the results showed that supplementation of diet with vitamin e and oregano and thyme essential oils not influenced on average body weight at 42 days of age, however addition of 400 ppm of oregano eesential oil significantly increased (p<0.05) the average body weight when compared with the control group at 24 days of age. the inclusion essential oils of thyme and oregano in diets did not affect on daily weight gain, daily feed intake, feed conversion ratio, carcass characteristics and liver superoxide dismutase activity of the chickens (p>0.05). supplementation of diet with 400 ppm thyme and oregano essential oils and 200 ppm vitamin e significantly increased (p<0.05) glutathione peroxidase activity in liver when compared to control group. birds received thyme and oregano essential oils in the diet, had lower (p<0.05) malondialdehyde concentration in liver than control group. all dietary treatments increased (p<0.05) total antioxidant capacity and decreased (p<0.05) malondialdehyde concentration in serum when compared with the control group except group of containing 200 ppm thyme essential oil. addition of oregano essential oil, 200 ppm thyme essential oil and vitamin e significantly decreased (p<0.05) serum cholesterol compared with the untreated control, also all treatments decreased (p<0.05) serum ldl concentration. these results suggested that supplementation of thyme and oregano essential oils to broiler diets tended to increase growth rate, improved antioxidant status, decreased serum ldl and cholesterol, and these could be consider as a natural antioxidant in poultry diet