Abstract

One-day-old broiler chicks were vaccinated with live Newcastle disease (ND) vaccine incorporated in oil alone or in killed-in-oil ND vaccine. Incorporation of live vaccine in oil emulsions was carried out just prior to vaccination. Live-in-oil ND vaccine containing 106.0 median embryo lethal doses (ELD50/dose induced the same protection following challenge and the same level of antibody at 42 days post-vaccination as did commercial killed-in-oil ND vaccine containing about 250 times as much antigen (108.4 ELD50/dose). Incorporation of live ND vaccine in killed-in-oil vaccine contributed markedly to protection rates and antibody levels, as compared to those obtained following vaccination with killed-in-oil vaccine only. One-day-old turkey poults also showed the advantage of incorporation of live ND vaccine in killed-in-oil vaccine when challenged 3 months post-vaccination. One-day-old broiler chicks, vaccinated with live ND and infectious bursal disease vaccine (IBD) incorporated in killed-in-oil combined ND + IBD vaccine, showed better protection against challenge with IBDV and higher antibody levels to NDV as compared to vaccination with killed-in-oil vaccine alone.

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