[Associated vaccination of poultry against infectious bronchitis, Newcastle disease and infectious bursitis].

: The effectiveness of immunity was studied following a mixed vaccination with live vaccines against infectious bronchitis (strains H120 and H52), Newcastle disease (strain La Sota), and infectious bursitis (strain Th75Vn82). The three vaccines were applied simultaneously via the drinking water, through the spray method, and nasally. Experiments were carried out with a total of 31,466 birds: broilers, growing layers, broiler parents--all without preliminary treatment with biopreparations. Immunity against Newcastle disease was followed up through the hemagglutination-inhibition test and challenging with a virulent virus; against infectious bursitis--through immunodiffusion in agar gel after Ouchterlony; and against infectious bronchitis--through virus-neutralization with strain Beaudette. The birds were treated with mixed vaccines in the following combinations: infectious bronchitis--Newcastle disease; infectious bursitis--Gumboro; infectious bronchitis, Newcastle disease, Gumboro. The simultaneous application of live vaccines against infectious bronchitis, Newcastle disease, and infectious bursitis was shown to be well tolerated with no harmful aftereffects whatever. The immunity built up with the simultaneous use of the three vaccines was not inferior in effectiveness to that conferred with the use of two vaccines or only one of them.