Data from an epidemiological study in Ontario, involving 304 dairy herds, were used to identify associations between selected production indices and
lipoarabinomannan antigen serological test results for
paratuberculosis (
LAM-ELISA). Analyses were conducted at both the herd and individual cow levels of organization. After analytically controlling for management and cow factors in the respective regression models, positive serological
paratuberculosis status (as defined by the
LAM-ELISA test), was associated with higher milk somatic cell counts at both the herd average (p less than 0.01), and individual cow levels of organization (p less than 0.0001). In contrast,
LAM-ELISA test results were consistently not associated with calving intervals in either the herd average or individual cow level analyses. Associations between
LAM-ELISA results and milk production were inconsistent. No associations were found at the herd level of organization, and
LAM-ELISA results were not associated with a change in breed class average (BCA) for milk, between the previous and the most recent lactations of individual cattle. However, at the individual cow level,
LAM-ELISA results were positively associated with higher milk production as measured by the current BCA (p less than 0.05), and individual cow average kg of milk produced per year of life since two years of age (p less than 0.0001).