Field evaluation of a sing‐dose bivalent vaccine of porcine circovirus type 2b and Mycoplasma hyopneumoniae

BACKGROUND: The field efficacy of a bivalent vaccine containing porcine circovirus type 2b (PCV2b) and Mycoplasma hyopneumoniae was evaluated on three pig farms. METHODS: Three pig farms were used, two of which had a history of subclinical PCV2 and clinical M. hyopneumoniae infections between 84 and 126 days of age while concurrent porcine circovirus‐associated disease and clinical M. hyopneumoniae infection between 70 and 105 days of age. Each farm vaccinated pigs with a single dose of a bivalent vaccine at 10 days of age while unvaccinated pigs were administered a single dose of phosphate buffered‐saline at the same age. RESULTS: Vaccination improved growth performance and reduced clinical scores significantly (p < .05) when compared with unvaccinated animals. The amount of PCV2d loads in blood and M. hyopneumoniae loads in nasal swabs of vaccinated animals were also significantly lower (p < .05) when compared with unvaccinated animals. Immunologically, vaccinated groups elicited a significantly higher (p < .05) level of protective immunity against PCV2d such as neutralizing antibodies and interferon‐γ secreting cells (IFN‐γ‐SC), as well as protective immunity against M. hyopneumoniae such as IFN‐γ‐SC when compared with unvaccinated animals. Pathologically, vaccination significantly lowered (p < .05) the scores of M. hyopneumoniae‐induced pneumonia and PCV2‐associated lymphoid lesions when compared with unvaccinated animals. CONCLUSIONS: The evaluated bivalent vaccine provided good protection against PCV2d and M. hyopneumoniae infection under field conditions.