There is no IBD vaccination schedule that can be routinely recommended. Factors influencing a vaccination schedule include:
- Type of chicken to be vaccinated (broiler or commercial layer).
- Level of MDA. The higher the start level of MDA the later the age at which vaccination is possible.
- Uniformity of MDA. If the variation in MDA levels is too high (CV>30%) a second IBD live vaccination is required to effectively immunise the flock.
- MDA breakthrough titre of the vaccine being used (intermediate or intermediate plus).
- Field pressure.
Choice of live vaccine to be used depends on:
- Virulence of field infection (Mild and Intermediate vaccine strains have poor efficacy against very virulent IBDV as these vaccines cannot be administered at an early age due to MDA interference. Vaccination is thus too late for field infection).
- Age of chickens to be vaccinated. (The earlier the vaccination the higher the level of MDA, requiring a stronger vaccine).
- Age at which Gumboro outbreak occurs. (Early outbreaks require earlier vaccination, refer point above).
Live IBDV vaccines are suitable to be administered by mass application. Drinking water route is the most common method.