Monitoring changes in association between salmonella-serology and microbiology over time
We found a strong correlation between seroprevalence in finishing herds and the number of positive pen samples in pig herds in level 2 or 3 in the Danish Salmonella Surveillance program. Several times during the period we observed, that the association, although always present, changed from one month to the following month. We found indications of a seasonality in the association, indicating, that late winter we would isolate more Salmonella for a given seroprevalence compared to late summer. Herds using home-mixed meal feed had less positive pen faecal samples for a given seroprevalence than herds using pelleted, purchased feed.