Comparison of the disease incidences of Finnish Ayrshire and Finnish Black and White dairy cows.

Finnish Ayrshire and Finnish Black and White cows were compared regarding the incidences of early and late mastitis, parturient paresis, ketosis, ovarian disorders, metritis and the risk of having a test-day somatic-cell count >200,000 cells ml(-1) at any of the first three monthly test days in lactation. In a retrospective cohort study 101,793 cows from 5844 tie stalls and 11,811 cows from 437 loose-housing systems from all over Finland were followed from calving in 2000 until the end of lactation. The observed incidences of those cows were then analysed using generalised linear mixed models. Finnish Black and White cows had higher incidences of all diseases except ovarian disorders. Although the differences were statistically significant in all models except metritis and early mastitis in loose-housing systems, they were, in our view, only important on the national level (for the breeding organisations), and of little importance for the farmers.