Background: The aim of this study was to determine the optimal vaccination strategies for the control of porcine respiratory disease complex (PRDC) caused by Mycoplasma hyopneumoniae, porcine reproductive and respiratory syndrome virus (PRRSV), and porcine circovirus type 2 (PCV2) in case of early mycoplasmal infection.
Methods: A total of 120 pigs were randomly divided into 6 groups (20 pigs per group). Four separate vaccine regimen groups were selected. Pigs from the four vaccinated groups were challenged with M. hyopneumoniae at 28 days old followed by a challenge of PRRSV or PCV2 at 49 days old.
Results: Regardless of PRRSV or PCV2 vaccination, pigs vaccinated with one of the M. hyopneumoniae vaccines at 7 days old had a significantly better growth performance over the whole length of the study compared to pigs vaccinated with a second M. hyopneumoniae vaccine at 21 days old. Vaccination of pigs with M. hyopneumoniae at 7 days and PRRSV at either 7, 14 or 21 days old resulted in significantly reduced PRRSV viremia and lung lesions compared to vaccination of pigs with M. hyopneumoniae and PRRSV at 21 days old.
Conclusions: The efficacy of the PRRSV MLV vaccine is influenced by the different timing of M. hyopneumoniae vaccination whereas the efficacy of the PCV2 vaccine is not. This experiment study demonstrated that early vaccination with a M. hyopneumoniae vaccine should be the highest priority in order to control M. hyopneumoniae and PRRSV infection in cases of early M. hyopneumoniae infection.
Keywords: Mycoplasma hyopneumoniae; porcine circovirus type 2; porcine reproductive and respiratory syndrome virus; porcine respiratory disease complex.
© 2020 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.