An Ulster 2C strain-derived Newcastle disease vaccine: vaccinal reaction in comparison with other lentogenic Newcastle disease vaccines.

Vaccinal reaction and seroresponse induced by an Ulster 2C strain derived Newcastle disease (ND) vaccine (ND) (PoulvacR NDW Broiler) were compared with those due to three other lentogenic ND vaccines (NDP, LZ58 and Clone 30) used in broilers in the Netherlands. Comparisons were made in SPF-WL hens and commercial broilers with maternally derived antibodies, using a fully standardized model. The criteria used were body weight gain and mortality rate following vaccine aerosol exposure and susceptibility to experimentally induced Colibacillosis. The NDW vaccine was the mildest, followed by Clone 30-, LZ58- and NDP vaccine. Although the seroresponse of SPF-WL hens exposed to NDW vaccine was significantly less than that induced by the other vaccines, the response was still substantial. Seroresponse to NDP-, LZ58- and Clone 30 vaccine did not differ significantly mutually. In broilers, serores-ponses to NDW- and Clone 30-vaccine were similar.