cm 330 cm). All birds were provided with uniform floors, electric lamps, feeders and gutters. The average room temperature in the daytime was 30.272.5 1C (summer season) and the lighting period was 22 h. The animals were reared according to the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching, and this study was approved by the university's Animal Care and Use Committee.
One-day-old chicks were inoculated for Newcastle disease (ND) and infectious bronchitis (NDþIB). B1 strains were inoculated at 7 days, and the ND inactive vaccine was injected on days 12 and 21 of the experiment.