Lack of evidence for fecal shedding of Mycobacterium avium subsp. paratuberculosis in calves born to fecal culture positive dams

Abstract

The objective was to detect presence of calves excreting Mycobacterium avium subsp. paratuberculosis (MAP) in their feces as a consequence of being born to MAP fecal culture positive (vs. negative) dams. For each cow that was about to calf, approximately 10g of feces was collected manually by the herdsmen from the rectum using a disposable plastic examination sleeve within 48-72h prior to actual calving. Between 1 and 3d of birth, herd personnel collected approximately 10g of fecal samples followed by monthly visits to the farm at which time 10g of fecal samples were again collected by study investigators from each calf at approximately 30, 60 and 90d of age. Mycobacterium avium subsp. paratuberculosis was recovered from 8% (5/60) of the cows that gave birth to calves. However, MAP was not recovered from any of the fecal samples (0/240) collected from study calves. Findings of the present study suggest lack of evidence for fecal excretion of MAP in calves born to fecal culture positive (vs. negative) dams in a heavily infected herd.