Evaluation and comparison of two methods of abattoir surveillance for detection of ovine Johne’s Disease.

Abstract

This project was designed to determine whether properties infected with ovine Johne’s disease (OJD) could be identified by routine monitoring of cull sheep at abattoirs for lesions of OJD or the presence of Mycobacterium avium subsp. paratuberculosis. Trained inspectors were stationed in abattoirs to examine not less than 50% and up to 95% of the abdominal viscera from all lines of adult sheep slaughtered during each kill shift (about 10 to 15 lines per shift at the two major export abattoirs). Where visible lesions suggestive of OJD were observed, fixed tissue samples were taken for confirmatory histopathology from up to three suspect sheep in each suspect line. Inspectors were not told the identity of the trial lines, but were aware that there was a trial line to be killed during the particular shift. Tied-off loops of terminal ileum were also taken from 10 randomly selected sheep in each line of sheep killed during the shift for pooled intestinal culture (PIC). The results of this trial indicate that visual and tactile monitoring of the viscera of cull sheep at slaughter for lesions suggestive of ovine Johne’s disease is a highly sensitive and reliable strategy for the detection of OJD infected flocks in which deaths from OJD are occurring.