Efffects of thyme (Thymus vulgaris L.) essential oil on performance, serum metabolites and immune system in broiler chickens under heat stress

This study was conducted in order to evaluate the effect of Thyme (Thymus vulgaris L.) essential oils on performance, carcass characteristics, serum metabolites and immune response in broiler chickens under heat stress. A total of 400 male broilers (Ross-308) were divided into 4 treatments with 5 replications of 20 birds per each. Experimental treatments were as follow: Control diet without additive and diets containing 0.1, 0.15 and 0.2 % of thyme essential oil. The results showed that supplementation of diet with thyme essential oils had not significant effect on average body weight daily weight gain, daily feed intake, feed conversion ratio, carcass characteristics (P>0.05). Addition of thyme eesential oil to broilers diet not influenced (p>0.05) serum metabolites (gluose, albumin, protein, triglyceride and VLDL), However significantly decreased (P<0.05) serum cholesterol and LDL concentration and significantly increased (P<0.05) HDL concentration. Supplementation of diet with thyme essential oils significantly increased (P<0.05) antibody response versus ND disease and sheep red blood cell (SRBC) in broiler chicks under heat stress. These results suggested that supplementation of diet with thyme essential oil tended to increase growth rate, immune system reinforcement, decreased serum LDL and cholesterol, and these could be consider as a growth promoter immune response amplifier in broilers diet under heat stress.