Proceedings of the 10th International Colloquium on Paratuberculosis

#235
Update on a Voluntary Johne’s Disease Control Program in Ontario and Western Canada
Ulrike Sorge, David Kelton, Kerry Lissemore, Ann Godkin, Steve Hendrick, Scott Wells
University <strong>of</strong> Guelph, Canada; Ontario Ministry <strong>of</strong> Agriculture, Food and Rural Affairs, Canada; University <strong>of</strong>
Saskatchewan, Canada; University <strong>of</strong> Minnesota, USA
In 2005-07 a voluntary Johne’s disease (JD) risk assessment (RA) control program was introduced to dairy
producers in Ontario and Western Canada. The program included a RA and JD milk ELISA herd test. The aim
<strong>of</strong> this study was to evaluate this RA based control program. Of <strong>the</strong> 499 contacted herds, 240 agreed to participate
in this follow-up study and to re-test <strong>the</strong>ir entire milking herd with a JD milk ELISA test more than 2 years
after <strong>the</strong> initial RA. The data collection is ongoing and so far 154 herds have retested <strong>the</strong>ir milking herd with a
milk ELISA test.
The preliminary results indicate a decline in <strong>the</strong> average within-herd test-positive prevalence. Linking
<strong>the</strong> current within-herd prevalence to management practices recorded with <strong>the</strong> RA from 2005-07 indicates
that farm-level hygiene and <strong>the</strong> purchase <strong>of</strong> cows are important areas for JD spread. Herds that purchased
cows, not bulls or heifers, in <strong>the</strong> 5 years prior to <strong>the</strong> RA showed higher prevalences today than closed herds.
Interestingly, herds that asked about <strong>the</strong> JD history <strong>of</strong> <strong>the</strong> seller’s herd tended to have lower prevalences than
herds that did not inquire. The recorded hygiene levels on farm, in particular for <strong>the</strong> calving area, were also
associated with a herd’s current prevalence – <strong>the</strong> lower <strong>the</strong> farm scored two years ago (i.e., <strong>the</strong> cleaner), <strong>the</strong>
lower <strong>the</strong> test-positive prevalence at present. Herds utilizing individual boxstalls had lower prevalences today
than herds with group calving pens. But also o<strong>the</strong>r areas, like manure contamination <strong>of</strong> feeders and waterers
for weaned heifers and cows, were associated with increased apparent prevalence in <strong>the</strong> herds current test.
Culling <strong>of</strong> JD milk test-positive cows was not linked to greater decrease in JD within-herd prevalence. In
conclusion, <strong>the</strong> program identifies risk areas correctly.
200