Association between Mycobacterium avium subsp. paratuberculosis infection and culling in dairy cattle herds

The present study was designed to analyse the causes for culling in dairy herds with different Mycobacterium avium subsp. paratuberculosis infection status and to compare these causes with those observed over the general dairy cattle population. During 2009, causes for culling were registered in two different groups of farms: (1) farms with seropositive cows for three consecutive years (2007-2009) but where Mycobacterium avium subsp. paratuberculosis has not been isolated from any of the fecal samples collected and (2) farms with Mycobacterium avium subsp. paratuberculosis seropositive cows for three consecutive years (2007-2009) and where the bacteria has been isolated from at least one fecal sample. Causes for animal loss were compared between both groups and between them and the general dairy cattle population by means of regression analysis. The distribution of culling reasons was different between infected herds (both bacteriologically positive and negative) and the general population. The percentage of losses seemed to be higher in infected herds from the first parity on. The most remarkable difference among groups was observed in losses due to "death/urgent slaughter".