Fig. 1

Prevalence of subclinical mastitis (SCM) and chronic subclinical mastitis (CSCM) in years 1991, 2001 and 2010. Prevalence of subclinical mastitis (SCM) and chronic subclinical mastitis (CSCM) of dairy cows in the Finnish national health monitoring and milk recording system in 1991 (SCM n = 27,296 and CSCM n = 10,427), 2001 (SCM n = 67,804 and CSCM n = 34,155) and 2010 (SCM n = 51,872 and CSCM n = 29,070). A cow was assumed to have SCM in the study if it had a composite milk SCC ≥200,000 cells/ml in at least one of the four test milkings for each study year. A cow was assumed to have CSCM if it had a composite milk SCC ≥200,000 cells/ml in three or all four test milkings during the study year