Background: Infection with Mycobacterium avium subspecies paratuberculosis (MAP) has been associated with\nreductions in milk production in dairy cows and sub optimal fertility. The aim of this study was to highlight the\nproduction losses associated with testing MAP ELISA positive in Irish dairy cows. Secondary objectives included\ninvestigation of risk factors associated with testing MAP ELISA positive. A survey of management practices on study\nfarms was also conducted, with examination of associations between management practices and herd MAP status.\nBlood samples were collected from 4188 breeding animals on 22 farms. Samples were ELISA tested using the ID Screen\nParatuberculosis Indirect Screening Test. Production parameters examined included milk yield, milk fat, milk protein,\nsomatic cell count, and calving interval. The association between MAP ELISA status and production data was investigated\nusing multi-level mixed models. Logistic regression was used to identify risk factors for testing JD blood ELISA positive at\nindividual cow level and to identify associations between farm management practices and herd MAP status.\nResults: Data were available for 3528 cows. The apparent prevalence recorded was 7.4 %. Mixed model analysis revealed\nno statistically significant association between testing MAP ELISA positive and dairy cow production parameters. Risk\nfactors associated with testing positive included larger sized herds being over twice more likely to test positive than\nsmaller herds (OR 2.4 P = <0.001). Friesians were less likely to test positive relative to other breeds. A number of study\nfarmers were engaged in management practices that have previously been identified as high risk for MAP transmission\ne.g., 73.1 % pooled colostrum and 84.6 % of study farmers used the calving area to house sick animals throughout the\nyear. No significant associations however, were identified between farm management practices and herd MAP status.\nConclusion: No production losses were identified; however an apparent prevalence of 7.4 % was recorded. With the\nabolition of EU milk quotas herd size in Ireland is expanding, as herds included in this study were larger than the\nnational average, results may be indicative of future JD levels if no JD control programmes are implemented to minimise\ntransmission.
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