Management risk factors associated with calf diarrhea in Michigan dairy herds.

A study was conducted to examine the relationships between various dairy herd management practices and the monthly incidence density of calf diarrhea. The data were collected during a recent 2-yr prospective cohort study by the Michigan National Animal Health Monitoring System. The data were statistically analyzed, and predictive models were developed. For herds with 10 to 49 adults cows, variables predicting an increase in the incidence of diarrhea in calves were number of young stock in the herd, incidence of respiratory disease in calves, and cumulative incidence of vaccinations for calves to prevent diarrheal disease. Increased numbers of routine veterinary visits to the farm were associated with decreased incidence of calf diarrhea. For herds with 50 to 99 adult cows, the positive predictor variable was incidence of respiratory disease in calves. Negative predictor variables were used of individual calving areas and removal of bedding between calvings. For herds with 100 to 199 adult cows, positive predictor variables were cumulative incidence of vaccinations for calves to prevent diarrheal disease and number of young stock in the herd. For herds with > 200 adult cows, positive predictor variables were use of individual calving areas, number of routine veterinary visits to the farm, and incidence of respiratory disease in calves. These variables accounted for 13.1, 17.7, 7.4, and 64.2% of the variability in the incidence of calf diarrhea in the respective herd size groups.