Enhancement of humoral immune responses to inactivated Newcastle disease and avian influenza vaccines by oral administration of ginseng stem-and-leaf saponins in chickens.

Newcastle disease (ND) and avian influenza (AI) are common in the poultry industry. The objective of this study was to evaluate the effect of oral administration of ginseng stem-and-leaf saponins (GSLS) on the humoral immune responses of chickens to inactivated ND and AI vaccines. In experiment 1, oral administration of GSLS at a dose of 5 mg/kg of BW for 7 d on the immune response in chickens intramuscularly injected with inactivated ND vaccine was evaluated. Results showed that GSLS significantly increased the antibody level against ND in the serum of chickens. In experiment 2, the same regimen of GSLS was administered to chickens inoculated with inactivated AI vaccines, and an enhanced serum antibody response to AI vaccination was also observed. Considering the safety of GSLS, because no adverse effect was found throughout the experiments, GSLS may be a promising oral adjuvant to improve immunization in poultry.