Dry aerosol vaccination against Newcastle disease: II. Serological response in chicks.

Day-old chickens with Newcastle disease maternal antibodies are separated in two batches. One batch (S) is vaccinated by liquid spray method with HB1 strain: the other one (NS) is not vaccinated. At 2, 3 or 4 weeks subgroups from S and NS batches are vaccinated with HB1 strain by dry aerosol method. Serological controls reveal an important increase of Newcastle antibodies within two weeks after dry aerosol vaccination. Then a drop of the antibody quantities is observed during weeks 2 to 4 post dry aerosol vaccination. In the following weeks, the antibody level increases very slowly.