Can sheep become infected by grazing pasture contaminated by cattle with Johne's disease?

Authors: Hamel KL, Ayling JM, Ris DR
Publication: New Zealand Veterinary Journal, Volume 35, Issue 8, pp 137, Aug 1987
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant, Sheep
Subject Terms: Bacterial, Disease transmission, Epidemiology, Mycobacterial, Wasting disease/disorder, Infectious disease, Disease/defect, Nutrition/metabolism, Pasture/crop
Article class: Correspondence

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Abstract: Transmission of Johne`s disease (JD) under natural conditions from sheep to cattle has been demonstrated in Iceland but not in New Zealand. The reverse, sheep becoming infected with Mycobacterium paratuberculosis of bovine origin, has been shown experimentally with large inocula (c. 5 x 10<sup>9</sup> organisms/lamb), but not under natural conditions. It could be important in New Zealand where sheep may be used to “clean up” pasture grazed by paratuberculous cattle. This report describes the infection of sheep with bovine Mycobacterium paratuberculosis strains under natural conditions. Over a period of two years six Romney ewes (yearlings when first introduced) have been rotationally grazed behind cattle with clinical Johne`s disease (including scours). The area involved consisted of four hectares subdivided into six paddocks. Monthly faecal samples from each sheep were cultured for M. paratuberuculosis organisms. At the conclusion of the trial, the sheep were transferred to concrete pens for a week in order to eliminate recently ingested JD bacilli from their digestive tracts…

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