Effect of in ovo vaccination with Newcastle disease virus on hatchability and antibody titres in immunodivergent broiler lines

Humoral immune response to Newcastle Disease (ND) vaccination was evaluated in two immuno-divergent broiler lines (Low Sheep Red Blood Cell Line, LSRBC and High Sheep Red Blood Cell Line, HSRBC). In ovo vaccination was done on 18^th embryonation day (ED) by amniotic sac route in the first sub-group of each line, whereas the second and third sub-groups acted as conventional ND vaccinated and unvaccinated groups, respectively. The percent hatchability was better in HSRBC eggs than in LSRBC eggs. In ovo vaccinated group had lower hatchability than the other groups. Chick to egg weight ratio was significantly higher in immuno-divergent lines than that of the control line. At 0 day of hatch, the HI titer against ND in the control line was significantly higher than the LSRBC and HSRBC lines. Even though from day 4 to 21^st day, there was no significant difference between lines, at 28^th day of age, the HSRBC line showed a significantly higher titer than all other groups. From the 10^th day onward, the in ovo vaccinated groups recorded higher titers than conventionally vaccinated groups and by 28^th day the difference was significant. It may be inferred that genetic selection for better humoral immune response capabilities together with in ovo vaccination may provide a better alternative for management of ND in poultry.