Efficacy of Two Commercial Ready-To-Use PCV2 and Mycoplasma hyopneumoniae Vaccines under Field Conditions

SIMPLE SUMMARY: Porcine Circovirus Type 2 (PCV2) and Mycoplasma hyopneumoniae are widespread pathogens which cause a negative health impact on swine and thus lead to important economic losses in farms. Vaccination is the main preventive measure for both infections and, since the recommended vaccination programs against both pathogens are very similar, bivalent vaccines are commercially available. However, the immune status of the sows against these infections could interfere in the efficacy of these products. The aim of this study was to assess the efficacy of two ready-to-use vaccines against PCV2 and M. hyopneumoniae in a herd positive to both infections under field conditions, considering the sow parity of the studied piglets. Both vaccines were efficient in preventing the development of PCV2 viremia, M. hyopneumoniae lung lesions and improving pig growth. Nevertheless, only one of them showed a significant improvement in the average daily weight gain and in the reduction of lung lesions when compared to the unvaccinated group. Sow parity did not interfere in the obtained outcomes. Considering the used vaccine, the anti-PCV2 antibody response was slightly different in pigs from primiparous sows than in those from sows with a higher parity number. ABSTRACT: Porcine Circovirus Type 2 (PCV2) and Mycoplasma hyopneumoniae are economically important pathogens in swine farms. Vaccination is the main preventive measure for both infections. In order to test two ready-to-use bivalent vaccines, 646 piglets from a herd actively infected with both pathogens were stratified according to the sow parity number and randomly assigned to three groups: A and B were vaccinated with two different vaccines, respectively, while C remained as the unvaccinated control. Vaccine efficacy was assessed based on the weight, average daily weight gain (ADWG), degree of lung lesions, presence of PCV2 viremia by qPCR and presence of PCV2 and M. hyopneumoniae antibody levels by ELISA. Our data revealed that the sow parity did not influence the vaccine outcomes. Good results for most of the analyzed parameters were observed in both vaccinated groups. ADGW and final weight were higher and lung lesions were less evident in both vaccinated groups than in the control one, but only Group A showed a significant improvement. PCV2 viremia was not detected in Group A, but it did appear in Group B coinciding with its peak in Group C. Finally, both the PCV2 and M. hyopneumoniae serological patterns differed depending on the employed vaccine.