The Effect of Rosemary, Thymus and Satureja Essential Oils, Vitamin E and Vegetable Oils on Immune System and Intestinal Microflora of Broiler Chicken

BACKGROUND: Antioxidant compounds and unsaturated fatty acids play an important role in improving the immune response and intestinal microflora in broiler chickens. Objectives: The aim of this study was to investigate the effects of different sources of antioxidant and soybean and rapeseed oils on humoral immune responses, intestinal microflora and some of the blood parameters of broiler chicken. Methods: A total of 480 male broiler chicks (Ross 308) were randomly allocated in a factorial arrangement (2×5) based on a completely randomized design with 10 treatments and 4 replicates during 42 days of age. Experimental factors consisted of different sources of antioxidant (rosemary, thymus and satureja essential oils at level of 300 ppm and vitamin E at concentration 200 mg/kg and without antioxidant) and vegetable oils (soybean and rapeseed oils at concentration of 4 percent of diet). Immune characteristics and intestinal microflora population were evaluated. Results: The use of different soybean and rapeseed oils had no significant effect on antibody titer (P>0.05) but the use of antioxidants improved immune responses against Newcastle disease (P<0.01). Also, the use of rosemary, thymus and satureja essential oils increased serum level of blood high density lipoprotein and reduced blood low density lipoprotein (P<0.001).  Furthermore, the concentrations of cholesterol and triglyceride increased in without  antioxidant treatment (P<0.001).Also, use of antioxidant treatments caused significant decrease of heterophil to lymphocyte ratio (P<0.05), then these result are consistent with the immune response against Newcastle disease. Furthermore, escherichia coli to lactic acid bacteria ratio increased in rosemary and thymus essential oils treatments compared with without antioxidant treatment (P<0.05). Conclusions:The use of dietary soybean and rapeseed oils did not have a significant effect on different traits of broiler chicken, but adding dietary antioxidants improved immune responses and intestinal microflora and in between different antioxidants, the use of essential oils compared with vitamin E  induced significant improvement of traits.