ce:italic>Mycoplasma bovis/ce:italic> and bovine respiratory disease: A risk factor study in Australian feeder cattle

摘要

Mycoplasma boviscan be a bacterial inhabitant of the upper respiratory tract of healthy bovines. In body regions other that the upper respiratory tract however,M. bovisis associated with a number of clinical syndromes such as bovine respiratory disease (BRD). This study used two enzyme-linked immunosorbent assays to assess the sero-status ofM. bovis-specific antibodies in Australian feeder cattle at the time of feedlot induction and at approximately 42 days on feed (follow-up). The apparent sero-prevalence ofM. bovis-specific antibody at induction was estimated to be 3.5% (95% confidence interval [CI] 2.0–5.0%, 47/1354) and 25.3% (95% CI 21.9–28.8%, 343/1354) at follow-up. Exposure toM. bovisbetween induction and follow-up as demonstrated by an increase in serum antibodies was estimated to be 19.4% (95% CI 16.2–22.6%, 261/1349).Risk factors associated with sero-positivity at feedlot induction included the region where animals were 28 days prior to induction and saleyard exposure at least 27 days prior to induction. Risk factors associated with a sero-increase between induction and follow-up included breed, source region and access to water shared with an adjoining pen of animals. Of these, shared pen water was considered the most important (odds ratio [OR] 3.3, 95% CI 1.5–7.4, p?=?0.003). Animals exposed toM. bovisbetween induction and follow-up were at a substantially increased risk of BRD (OR 2.2, 95% CI 1.4–3.4, p?=?0.001).This is the first Australian study that has identified risk factors forM. bovissero-positivity and sero-increase and shown an association between sero-increase and the risk of BRD in the feeder cattle population. These findings suggest thatM. bovisis a significant pathogen in the Australian feeder cattle population. In addition, identification of defined risk factors associated with an increased risk of exposure toM. boviscan assist in the development of targeted control measures to reduce the economic impact ofM. bovisassociated disease and BRD in feeder cattle.