Comparison of humoral immune response and challenge protection of live oil adjuvanted, aqueous live and killed adjuvanted Newcastle disease (LaSota strain) vaccines in broiler chicks

Efficacv of live-in-oil Newcastle disease (ND) vaccine (half and full antigenic dose) was compared with aqueous live and ki-lled-in-oil ND vaccines using the ND virus LaSota strain in broiler chicks. Broiler chicks (7-day-old) were either vaccinated against ND with aqueous live, killed-in-oil, live-in-oil with half and with full antigen dose vaccines or were inoculated only with the oil adjuvant or kept as non-vaccinated controls (20 birds/group). Serum samples collected at weekly interval from day 1 to day 42 of their age were titrated for the presence of NDV antibodies by HI. The titres were higher in all the vaccinated groups than controls from 1 week after vaccination onward. The titres were higher in both live-in-oil with half and full antigen dose vaccines than aqueous live and killed-in-oil on day 28 and 35 post vaccination. Challenge with a velogenic field NDV (day 14 post vaccination) to 10 birds of each group gave higher protection (70-90%) in vaccinated chicks than controls. It is concluded that live-in-oil ND vaccine (half and full antigenic dose) gave higher titre over 35 days post vaccination than aqueous live and killed-in-oil ND vaccines in broiler chicks.