Detection of Mycoplasma hyopneumoniae in naturally infected gilts over time

•M. hyopneumoniae natural infection was assessed in gilts in a longitudinal study.•M. hyopneumoniae detection in gilts started at 110days of age.•Gilts were detected M. hyopneumoniae positive for 1–3 months in natural infections.•Presence of negative subpopulations in positive herds were observed. Mycoplasma hyopneumoniae causes a chronic respiratory infection in pigs and its transmission occurs mainly by direct contact and by vertical transmission (sow-to-piglet). The objective of this study was to assess the detection dynamics and persistence of M. hyopneumoniae natural infection in replacement gilts. Forty-four twenty-day-old gilts were selected from a M. hyopneumoniae positive farm and followed up to one day prior to their first weaning. Laryngeal swabs were collected every 30days, starting at day 20, for M. hyopneumoniae detection by real-time PCR, resulting in 12 samplings. Piglets born to selected females were sampled via laryngeal swabs one day prior to weaning to evaluate sow-to-piglet transmission. The M. hyopneumoniae prevalence was estimated at each one of the 12 samplings in gilts and a multiple comparison test and Bonferroni correction were performed. Bacterial detection in gilts started at 110days of age (doa) and a significant increase (p