Background: The use of traditional medicine against viral diseases in animal production has been practiced worldwide. Herbal extracts possess organic substances that would improve chicken body performance.
Aim: The current study was designed to evaluate the effect of either thyme or ginseng oil in regard to their immune-modulatory, antiviral, and growth promoter properties.
Methods: Two hundred and forty-one-day-old broiler chicks were allocated into eight equal groups as the following: group 1; nonvaccinated and nontreated and group 2; Newcastle disease virus (NDV) vaccinated and nontreated. Birds of groups 3 and 4 were treated with thyme oil (200 mg/l of drinking water for 12 hours/day) without or with NDV vaccination. Birds of groups 5 and 6 were treated with ginseng oil (200 mg/l of drinking water for 12 hours/day) without or with NDV vaccination. Birds of groups 7 and 8 were treated with a combination of ginseng oil (100 mg/l of drinking water) and thyme oil (100 mg/l of drinking water) for 12 hours/day. On the 35th day of life, birds in all the experimental groups were given 0.1 ml of a virulent genotype VIId NDV strain suspension containing 106.3 EID50/ml intramuscularly.
Results: Administration of ginseng and thyme oils each alone or simultaneously to birds either vaccinated or nonvaccinated elicited a significant improvement in body performance parameters. Administration of thyme and ginseng each alone or concurrently to vaccinated birds (Gp 4, 6, and 8) induced a higher hemagglutination inhibition (HI) titer of 6, 7.3, and 6.3 log2 at 21 days of age, 6.7, 7.6, and 7 log2, at 28 days of age and 7, 8, and 6.8 log2 at 35 days of age, respectively. Challenge with vNDV genotype VII led to an increase in the NDV-specific HI-Ab titers 10 days post challenge in all the experimental groups. In addition, thyme, ginseng oils, or a combination of them improved the protection from mortality in vaccinated birds; by 100%, 100%, and 90%, respectively, compared with 80% protection from mortality in vaccinated-only birds post-NDV challenge. Moreover, NDV-vaccinated birds treated either with thyme; ginseng or their combination showed negative detection of the virus in both tracheal and cloacal swabs and nonvaccinated groups that received oils showed improvement in vNDV shedding in tracheal and cloacal swabs.
Conclusion: It could be concluded that the administration of thyme and ginseng essential oils to broilers can improve productive performance parameters, stimulate humoral immunity against, and protect from vNDV infection.
Keywords: Chicken; Genotype VII; Ginseng; NDV; Thyme.