DEVELOPMENT AND APPLICATION OF A HYPERIMMUNE YOLK-FLUID AGAINST INFECTIOUS BURSAL DISEASE AND NEWCASTLE DISEASE.

Yolk was separated from eggs laid by healthy hens which were inoculated with infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) several times, and a combined hyperimmune yolk-fluid against IBDV and NDV was obtained. Its haemagglutination-inhibiting (HI) antibodies to NDV as well as neutralizing and precipitating antibodies to IBDV reached a high level. The results of experimental and field triab showed that inoculation of this combined antibody product could , within a short time, allow chickens to withstand IBDV and NDV challenge. When injected into chickens early in an outbreak of these diseases, it showed marked therapeutic efficacy.