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Evaluation of a vaccine against Mycoplasma gallisepticum in commercial broilers
Abstract:
The efficacy of live Mycoplasma gallisepticum (MG) vaccine against respiratory mycoplasmosis was studied in three laboratory trials with commercial broilers. Broiler chickens were infected with the F or R strain of MG by eyedrop at 1 day of age, and challenged by aerosol exposure to the R strain of MG along with eyedrop vaccination against Newcastle disease and infectious bronchitis at 30 or 34 days of age. Observations were made of macroscopic lesions, severity of airsacculitis, isolations of MG, serologic test results, clinical signs, and mortality. In all the vaccinated groups, the air-sac-lesion score was lower after challenge than in unvaccinated control chickens. After challenge the control group also had a higher number of MG isolations from the air sac than did the vaccinated chickens. There were no air-sac lesions observed in broilers before challenge in 2 of 3 trials.
Insights
A live Mycoplasma gallisepticum (MG) vaccine effectively reduced respiratory disease in broilers. Vaccinated chickens showed fewer airsac lesions and less MG in air sacs post-challenge.
Area of Science:
- Veterinary immunology
- Avian pathology
- Vaccine efficacy studies
Background:
- Mycoplasma gallisepticum (MG) causes significant respiratory disease in commercial poultry.
- Effective vaccination strategies are crucial for controlling MG outbreaks in broiler flocks.
Purpose of the Study:
- To evaluate the efficacy of a live Mycoplasma gallisepticum (MG) vaccine in commercial broilers.
- To assess the vaccine's impact on respiratory lesions, MG isolation, and clinical signs following challenge.
Main Methods:
- Three laboratory trials were conducted using commercial broiler chickens.
- Chicks were infected with MG strains and later challenged via aerosol, with concurrent vaccination for other diseases.
- Key observations included macroscopic lesions, airsacculitis severity, MG isolation, serology, clinical signs, and mortality.
Main Results:
- Vaccinated groups consistently exhibited lower air-sac-lesion scores compared to unvaccinated controls post-challenge.
- Fewer MG isolations from air sacs were recorded in vaccinated chickens after challenge.
- No air-sac lesions were detected in broilers before challenge in two out of three trials.
Conclusions:
- The live Mycoplasma gallisepticum vaccine demonstrates significant efficacy in protecting broilers against respiratory mycoplasmosis.
- Vaccination reduces disease severity, indicated by lower lesion scores and reduced MG shedding.
- This vaccine represents a valuable tool for managing MG in commercial broiler production.