Department of Veterinary Microbiology, CCS-Haryana Agricultural University, Hisar-125 004 (Haryana).
*Corresponding Author: # G-39, Sector-23, Sanjaynagar, Ghaziabad - 201 002 (U.P.)
In the present study, using infectious bursal disease virus (IBDV) infection in broiler chickens as a model, the antimicrobial and immunomodulatory effects of the two preparations viz., dried leaves powder and essential oil of the Ocimum sanctum (Shyama Tulsi) medicinal plant were evaluated. Birds were treated with predetermined safe dose of dried leaves powder @ 200 mg/bird daily and essential oil @10 μl/bird daily orally over a period of 25 days and infected experimentally at day 5 with 1 X 105 TCID50 dose of Georgia strain of IBDV. A reduction in viral replication in the target organ viz. bursa of Fabricius was observed in the birds treated with dried leaves powder as evidenced by marked reduction in gross and microscopic lesions of IBD and the reduced virus titre in bursa. In these birds, immunopotentiation as measured by increase in skin thickness for contact hypersensitivity response was also observed. However, the birds treated with dried leaves powder showed markedly lower antibody responses as measured by serum neutralization test and ELISA. This may be due to accelerated virus clearance in these chickens mediated through generalized enhanced cell mediated immune response. On the other hand, the birds treated with essential oil showed some toxic effects as evidenced by hemorrhages on thigh muscles. Thus the dried leaves powder of O. sanctum has the potentials to be effectively utilized as a feed supplement against some of the important poultry pathogens particularly IBDV, since it was found to inhibit the virus replication in vivo. However, the field applications of Ocimum sanctum will depend upon the results of studies in a larger population of birds and the outcome of similar studies against a number of other important pathogens of poultry.
