RELATIONSHIPS BETWEEN THE PRESENCE OF JOHNES-DISEASE AND FARM AND MANAGEMENT FACTORS IN DAIRY-CATTLE IN ENGLAND

The data collected by a postal questionnaire sent to 3772 randomly sel ected dairy farmers in England and the border regions in Wales were us ed to estimate the relationships between the presence of clinical John e's disease and farm and management factors associated with that disea se. Two binary outcomes (case reported in 1993, case reported in 1994) and 27 predictor variables were considered. Only two variables were c onsistently and significantly associated with clinical disease in mult ivariable analysis. Farms on which Channel Island breeds were predomin ant were associated with an increased risk of reporting disease (odds ratios (ORs) ranged from 10.9 to 12.9), The presence of farmed deer on the farm also increased the risk of reporting disease (ORs ranged fro m 15.2 to 209.3). There were other significant but inconsistent associ ations involving the source of replacements, age of first-offering hay , type of concentrate feed to calves, and calving in individual pens w hen the cows were at grass. Since Johne's disease is predominantly sub clinical, these contributing factors may play important roles in switc hing subclinical infection to overt disease. (C) 1997 Elsevier Science B.V.