Economic impact of paratuberculosis on milk production

Abstract

Paratuberculosis (Johne's disease) is a chronic inflammatory bowel disease, primarily affecting ruminants. The aetiologic agent is Mycobacterium avium subsp. paratuberculosis (MAP). The disease is characterised by persistent diarrhea, weight loss and protein-losing enteropathy. Paratuberculosis can cause significant economic loss in affected herds, as a result of reduced milk yield, increased incidence of mastitis, altered milk constituents, increased somatic cell counts, poor feed conversion, increased susceptibility to disease in general, reduced reproductive efficiency, premature culling and reduced cull cow values. The economic impact of paratuberculosis includes production losses due to sub-clinical and clinical cases, losses due to increased replacement of animals and costs of control measures. Due to the fact that most cases of paratuberculosis are subclinical and precise prevalence data are often lacking, it is difficult to assess the economic consequences of paratuberculosis. For instance, estimates of milk production losses are inconsistent. Some studies found equivalent or even higher milk productions in test-positive animals. Other studies showed losses in test-positive animals of up to 19.5% of the 0 to 305 days-in-milk production, depending on parity.