Use of an inactivated infectious bursal disease oil emulsion vaccine in commercial layer chicks.

Commercial layer chicks of different ages were inoculated with either one-fifth, two-fifths or a full dose of an inactivated infectious bursal disease oil emulsion vaccine and then challenged with virulent virus. The partial doses given at seven or 10 days old gave only partial protection. A full dose given at 10, 14 or 28 days old failed to give full protection but a full dose administered at seven days old protected all the chicks after each challenge.