|Brugh, Max - USDA-ARS; RETIRED|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 1997
Publication Date: N/A
Interpretive Summary: In studies to establish early immunity in chickens against two deadly viral diseases, Newcastle disease and avian influenza, oil-emulsion vaccines against these diseases were injected into chicken eggs 3 days before hatch. Effective vaccine dose volumes and needle sizes and lengths were found that had little or no effect on lowering hatchability. The immunity of the chickens was determined at 53 and 34 days of age by challenge with Newcastle disease and avian influenza viruses, respectively. Vaccinated chickens were protected against death and clinical signs when exposed to virus that killed all non-vaccinated control chickens. The vaccination process has the potential for automation, thus allowing large-scale rapid vaccination of chicks at cost effective rates. The overall result of this research should help to lower poultry production costs.
Technical Abstract: Inactivated oil-emulsion (OE) Newcastle disease (ND) and avian influenza (AI) vaccines were injected into 18-day-old white rock (WR) and white leghorn (WL) embryos to evaluate their immunologic efficacy and their effects on hatchability. Embryonating eggs were inoculated at 1.5 inches depth with various vaccine volumes and antigen concentrations. Serum hemagglutination-inhibition (HI) titers were first detected in chickens a 2 weeks posthatch. Protection against morbidity and mortality was demonstrated in chickens vaccinated as embryos and challenged with viscerotropic velogenic ND virus at 53 days of age or highly pathogenic AI virus at 34 days of age. In pooled groups from successive hatches, the hatchability of WR or WL embryos injected with 100 microliters of vaccine was not significantly different from unvaccinated hatchmate controls when needle gauges of 22, 20, and 18 were used. Seroconversion rates of chickens vaccinated as embryos ranged from 27% to 100% with ND vaccinatio and 85% to 100% for AI vaccination. Mean HI titers of chickens that seroconverted ranged from 1:25 to 1:422 for ND and 1:92 to 1:1280 for AI vaccine groups. It was concluded that acceptable hatchability, seroconversion rates, and protective immunity can be attained with in ovo inoculation of ND or AI OE vaccines, if the vaccines are prepared with sufficient antigen and administered properly.