ASSOCIATION BETWEEN DAM STATUS AND OFFSPRING MYCOBACTERIUM AVIUM SUBSPECIES PARATUBERCULOSIS INFECTION IN A LONG-TERM LONGITUDINAL STUDY

摘要

A longitudinal study was carried out, following a large cohort of dairy cows in six UK herds, recruited in 2012-2013. Individuals entering the milking herd were routinely monitored for presence of Mycobacterium avium subsp. paratuberculosis (MAP) using quarterly milk ELIS A testing. Using a Cox proportional-hazards regression model the relationship between time until first detection of infection and dam MAP status was investigated, allowing for both management and individual animal risk-factors. Themagnitude of the effect of dam status was then compared with that of other risk-factors in order to understand its relative importance. When compared to negative dams, and stratifying by herd, having a positive dam at time of calving more than doubled the hazard of testing positive. Further positive associations were found with dams becoming positive after the birth of the subject. Dam status had the largest effect on disease outcome.