Out of four groups of birds, group I was vaccinated with F strain of NDV and group II was vaccinated with inactivated oil adjuvanted R2B vaccine alone, group III was vaccinated with both F strain and inactivated oil adjuvanted R2B and the fourth group was kept as unvaccinated untreated control (UUC). Haemagglutination inhibition (HI) test was performed to determine the pre-vaccination and postvaccination antibody titres against NDV. A total of five chicks were sacrificed at day-old age to assess the level of maternal antibodies in the chicks. Thereafter, tests for the level of maternal antibodies of the unvaccinated chicks were carried out along with titration of serum samples of vaccinated groups of birds (I to III) for post vaccination titres at 7, 14, 21, 28 and 56 days of age. Maternal antibodies in the unvaccinated untreated control group (IV) rapidly declined, whereas in the vaccinated groups, antibody titres started to rise after 7–14 days of vaccination in F and combined F + R2B vaccinated groups, while antibody level of inactivated oil adjuvanted R2B vaccinated groups started to rise only after 21 days of vaccination. On challenge with a virulent strain of NDV at 8th week of age, the groups vaccinated with F + R2B (Group III) showed 100% protection as against 60% protection rate shown by the group vaccinated with F alone (Group I) while 80% protection rate was shown by the group vaccinated with R2B alone (Group III).
Birds, simultaneous vaccination, Newcastle disease
