The efficacies of two commercial Mycoplasma hyopneumoniae bacterins and porcine circovirus 2 (PCV2) vaccines were compared in conventional pigs immunized at different ages based on humoral response, pathological observation, and growth performance from birth to finishing (175 days of age) using a M. hyopneumoniae and PCV2 co-infection challenge model. One-week-old pigs (n=110) were randomly assigned to five groups: three vaccinated and challenged (VC), and one each of non-vaccinated and challenged (NVC) and negative control. A significant difference was found in the number of genomic copies of M. hyopneumoniae in nasal swabs and PCV2 in serum samples, the average daily weight gain (gram/pig/day) between 63 and 133 dpi, gross and histopathological lung lesion scores, histopathological lymph node lesion scores, and the immunohistochemical analysis of PCV2 among the three VC groups. The single dose schedule for M. hyopneumoniae bacterins and PCV2 vaccines have the advantages of (i) improving daily weight gain (122.4%) and slaughter weight (120.5%), and (ii) reducing the incidence of clinical signs and lung and lymph node lesions.
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