Field Evaluation of a Novel Combined Vaccine Against Porcine Circovirus Types 2a/d, Mycoplasma hyopneumoniae and Mycoplasma hyorhinis With an Emphasis on Growth Performance

Background A field efficacy trial was conducted on three farms to evaluate a novel combined vaccine containing porcine circovirus types 2a/d (PCV2a/d), Mycoplasma hyopneumoniae , and M. hyorhinis . Methods Three farms with a history of subclinical PCV2 infection, enzootic pneumonia, and polyserositis were enrolled. Each farm included 40 piglets (18 days old), which were randomly allocated to vaccinated or unvaccinated groups. Pigs in the vaccinated group received a single 2‐mL intramuscular dose of the combined vaccine at 21 days of age, while unvaccinated pigs received phosphate‐buffered saline. Results Vaccination significantly improved ( p < 0.05) body weight and average daily weight gain on all three farms compared with unvaccinated pigs. Vaccinated pigs mounted protective humoral and cellular immune responses against PCV2, M. hyopneumoniae , and M. hyorhinis . Furthermore, vaccination reduced viral and mycoplasmal loads in serum, laryngeal, and nasal samples and decreased the severity of associated lesions. Conclusions The combined vaccine demonstrated strong efficacy under field conditions, providing protection against subclinical PCV2 infection, enzootic pneumonia caused by M. hyopneumoniae , and polyserositis caused by M. hyorhinis . These findings support its potential as an effective intervention for improving both health and productivity in swine herds.