Effect of Oregano Essential Oil Combined with Live and Killed Newcastle Disease Vaccines on Immune Response in Broilers Chicks in Erbil, Iraq: A Comparative Study

This trial was conducted to evaluate the effects of oregano essential oil supplementation at the concentration of 50 mL/1000L of drinking water on immune response and growth performance in broiler chickens. A total of 390 one-day-old Rose chickens were housed together in six experimental boxes (n=65 each), including nonvaccinated groups and non-vaccinated oregano treated groups. Group A: vaccinated with LaSota vaccine via eye drop at 5-, 15-, and 28-day-old adding oregano essential oil in drinking water 1 day post-vaccination. Group B: vaccinated with LaSota vaccine via eye drop at 5-, 15-, 28-day-old only without oregano essential oil. Group C: vaccinated with inactivated Newcastle disease (ND) vaccine at 5-day-old via subcutaneous (SC) injection one dose adding oregano essential oil in drinking water 1 day post-vaccination for 3 days. Group D: vaccinated with inactivated ND vaccine at 5-day-old via SC injection one dose only without oregano essential oil. Group E: nonvaccinated as the control group. Group F: non-vaccinated and adding oregano essential oil for 3 days in drinking water as the control group. The effect of oregano essential oil in drinking water combined with two forms of live and killed ND virus vaccines on the immune responses and serum proteins was investigated in broiler chickens. The results showed the significant effect of oregano on the immune response of chicks in groups D and C that were vaccinated with the killed vaccine at 23- and 33-day-old. Based on the findings, a peak was recorded at 38- day-old with a significant difference (P<0.05) in vaccinated and non-vaccinated groups, as well as a significant increase in 38-day-old for group C (P<0.05), compared to other groups regarding the oregano effects on the immune response of groups. In addition, an increase in the serum protein was significantly different (P>0.05) in the vaccinated broiler chicks, and serum globulin showed a quantitative increase in the vaccinated broiler chicks, compared with non-vaccinated groups. However, the results showed that the effect of oregano was nonsignificantly different (P>0.05) and it had no beneficial effect on growth performance. The results of this study showed the effects of commercial Oregano supplementation (50 mL/1000L drinking water), which increased serum total protein, including globulin, and provoked the best immunological response to ND vaccinations in broiler chickens. More research is needed to develop a state that may beneficially affect the health and uniformity of chickens.