Use of infectious bursal disease vaccines in chicks with maternally derived antibodies.

Day-old chicks with maternally derived infectious bursal disease (IBD) antibodies were inoculated with IBD oil emulsion vaccine. The vaccine protected at least 85 per cent of the chicks when they were challenged at four weeks old with virulent IBD virus and at least 90 per cent of those challenged at seven weeks of age. There was no benefit in using a combination of the oil emulsion vaccine and a live IBD vaccine.