Immunization of Chickens for the Control of Infectious Bursal Disease

Six experiments were conducted involving 790 chickens inoculated with IBD (infectious bursal disease) vaccine produced at this station to determine a suitable age and route of vaccination. Vaccinated birds resisted a challenge dose that caused 10–20% mortality among unvaccinated challenged controls; whereas, there were no deaths among vaccinates. A total of 3,092,864 chicks in 135 flocks on 88 farms in Alabama and Mississippi were vaccinated at an average age of 5 days via the drinking water or intraocularly in initial trials. Mortality following vaccination averaged <0.78% during the reaction period (5 to 7 days) compared with an average 5% mortality in natural outbreaks on the same farms. There were no relapses or natural outbreaks in any of the 135 vaccinated flocks.