Key result
Administration of Marek's disease vaccines in ovo or at hatch did not significantly reduce the efficacy of infectious bronchitis vaccines given at hatch (protection 50.0-95.5% vs 55.0-77.3%).
Why the study?
Does the administration of Marek's disease vaccines in ovo or at hatch reduce the efficacy of infectious bronchitis vaccines in commercial broiler chickens?
Does the administration of Marek's disease vaccines in ovo or at hatch reduce the efficacy of infectious bronchitis vaccines in commercial broiler chickens?
p-value: p=<=0.05
Administration of high-titered Marek's disease vaccines either in ovo or at hatch does not adversely affect the efficacy of infectious bronchitis vaccination given at hatch in broiler chickens.
Supports co-administration in broiler chicks; leaves open field validation for commercial schedules.
Two experiments were conducted using commercial broiler chickens to determine if Marek's disease (MD) vaccines HVT/SB-1 and HVT plus CVI-988 given either in ovo or at hatch adversely affected the efficacy of infectious bronchitis (IB) vaccines (Ark and Mass serotypes) given by eyedrop on the day of hatch. Nonvaccinated negative controls and controls that received only IB vaccines were included in each study. Birds were challenged with either infectious bronchitis virus (IBV) Mass-41 or IBV Ark-99 on either day 26 or 27 of age. Protection was assessed 5 days post-IBV challenged by virus isolation from the trachea. The day of hatch mean antibody titer to IBV was 12,668 +/- 4704 and 2503 +/- 3243 by enzyme-linked immunosorbent assay in experiments 1 and 2, respectively. In each study, nonvaccinated controls had a significantly higher (P < or = 0.05) incidence (88%-100%) of IBV challenge virus isolation than did controls vaccinated for IB but not for MD. Analysis of data from both studies showed that protection to IB in groups that received only IB vaccines at hatch ranged from 55.0% to 77.3%, whereas protection to IB in groups receiving both MD and IB vaccines ranged from 50.0% to 95.5%. In both experiments and within IBV challenge serotype, broilers given MD vaccines (in ovo or at hatch) and IB vaccines at hatch had protection rates to IBV challenges that were not significantly less (P < or = 0.05) than IB protection rates of groups that received only IB vaccines at hatch. Analysis of these data shows that administration of high-titered MD vaccines either in ovo or at hatch did not affect the efficacy of an IB vaccination (serotypes Ark and Mass) given by eyedrop at hatch.
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Avakian et al. (2000) studied Marek's disease and infectious bronchitis. Marek's disease vaccines (HVT/SB-1 and HVT plus CVI-988) vs. Infectious bronchitis vaccines only was evaluated on Protection to infectious bronchitis assessed by virus isolation from the trachea (p=<=0.05). Administration of Marek's disease vaccines in ovo or at hatch did not significantly reduce the efficacy of infectious bronchitis vaccines given at hatch (protection 50.0-95.5% vs 55.0-77.3%).
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