Intra-farm risk factors for Mycoplasma hyopneumoniae colonization at weaning age.

The objective of this study was to identify intra-farm risk factors that affected the colonization with Mycoplasma hyopneumoniae at weaning age. Three farrow-to-wean farms were visited at least 5 times each. An average of 54 piglets were sampled at each visit and assayed by means of real-time PCR in nasal swabs. The proportion of PCR positive piglets was evaluated as a response to several variables including dam's PCR status, piglet serological status, and local climatic conditions during the lactation period, as well as other factors. All piglets at weaning age were negative to M. hyopneumoniae in 2 of the 3 farms. M. hyopneumoniae positive piglets were demonstrated in 5 of 7 weaning groups in 1 farm. The proportion of M. hyopneumoniae positive piglets in each weaning group at the positive farm was correlated with the proportion of positive dams in the group. The prevalence of M. hyopneumoniae at weaning increased with the piglet's age in the groups where at least one dam was positive. These results highlight the influence of the sow in the sow-to-piglet colonization process, as previously reported, and contribute to a more comprehensive understanding of the epidemiology of M. hyopneumoniae infections.