Effectiveness of two intramuscular combined vaccines for the control of Mycoplasma hyopneumoniae and porcine circovirus type 2 in growing pigs: a randomized field trial.

Mycoplasma hyopneumoniae and Porcine circovirus type 2 are two economically important pathogens affecting growing pigs. Control and prevention of both diseases can be accomplished by vaccination, together with biosecurity and good management practices. Many commercial vaccines are available. The aim of this study was to assess the efficacy of Hyogen® and Circovac® administered mixed at weaning and to compare this protocol with a competitor ready-to-use (RTU) vaccine. A randomised field trial was designed in a commercial farrow-to-finish farm located in France. A total of 641 pigs born from 54 different sows were included in this study. Piglets at weaning were allocated into three groups: the first one vaccinated with Hyogen® and Circovac® combined (group A), the second one vaccinated with a competitor RTU vaccine (group B) and the last one unvaccinated. Only minor local reactions for both vaccination groups could be observed which revealed a good safety of both protocols. Both vaccination schemes in this trial didn’t improve wean-to-slaughter growth performances but significantly reduced lung lesions, lung fissures and pleurisy at slaughter, produced a seroconversion for both M. hyopneumoniae and PCV-2 and significantly reduced the PCV-2 viral load in blood. When we compared groups A and B, we observed no significant differences in growth performances, mortality, clinical signs, percentages of affected lungs at slaughter, lung fissures and pleurisy, and no difference in pathogens detection. However, two statistical differences were observed between both vaccines: the mean lung lesion score and the percentage of extensive lung lesions were lower in group A. This is consistent with lower M. hyopneumoniae loads in the lower respiratory tract in pigs from group A but this difference was not statistically significant. Results reported in this case study must be considered with caution since it was done in only one farm. In this trial, Hyogen® and Circovac® mixed together under field conditions offered a successful protection of growing pigs and significantly decreased the extension of lung lesions during a natural field challenge when compared with a competitor RTU vaccine.