Field evaluation of tracer sheep for the detection of early natural infection with<i>Mycobacterium avium</i>subsp<i>paratuberculosis</i>

Abstract

These findings indicate that groups of unexposed 'tracer' sheep, tested by culture of tissues at slaughter 6 to 12 months after first exposure, might be a useful way to assess pasture infectivity in control programs for ovine Johne's disease.