MANAGERIAL RISK-FACTORS FOR INTRAMAMMARY COAGULASE-POSITIVE STAPHYLOCOCCI IN OHIO DAIRY HERDS

A stratified random sample of Ohio dairy herds was studied to relate h erd management and environmental conditions to intramammary infection with coagulase-positive staphylococci. Management and environmental co nditions were assessed by investigator observation and by interview wi th the dairy producers. Separate analyses for each of 70 management an d environmental independent variables identified many potential diseas e determinants. A logistic regression model used five model degrees of freedom to predict the prevalence of coagulase-positive staphylococci in more than 1% of quarters. Increased risk of infection with coagula se-positive staphylococci was associated with dirty udders, high-line milking systems, and less crowded housing conditions. Decreased risk o f infection was associated with a herd size of 50-100 cows.