A voluntary risk-based control program on paratuberculosis in dairy cattle was initiated in Denmark in 2006. Cows were categorized as high-risk (antibody-positive at least once within the last 3 tests) or low-risk animals based on the results of 3 to 4 annual milk ELISA detecting Mycobacterium avium ssp. paratuberculosis (MAP)-specific antibodies. High-risk animals require management practices aimed at decreasing calf exposure to MAP-contaminated colostrum and milk, and feces originating from these cows. Moreover, repeated test-positive cows are recommended for slaughter before next calving. The objective was to assess the effect of different management practices on the prevalence of MAP-specific antibodies. A questionnaire on management practices was distributed to 1,261 participating herds in December 2008. A total of 1,092 (87%) herd managers returned the questionnaire. Repeated prevalence data from 1,081 herds were available for a period up to 4.25 yr after the first test round. The changes in the prevalence of MAP-specific antibodies from the start of interventions were assessed using a hierarchical logistic model, where different management practices were assessed: a) culling of repeated test-positive cows, b) separation of high-risk from low-risk cows in calving areas, c) cleaning of calving areas after high-risk cows calved, d) removal of calves born to high-risk dams within 2h after calving, e) use of colostrum for feeding of heifer calves from low-risk cows only, f) use of waste milk for feeding of heifer calves from low-risk cows only, g) herd size, and h) proportion of purchased animals. Multivariable analyses suggested that only the proportion of purchased animals (>15% purchased animals as well as 0 to 15% purchased animals compared with no purchased animals in the herd), culling of repeated test-positive animals, and use of waste milk from specific cow groups influenced the decrease in prevalence of MAP-specific antibodies. The control program has been running for just 4.25 yr, and it is assumed that the full effect of the risk-based management practices will only be observed after 4 to 8 yr. Therefore, lack of association between some practices and decrease in prevalence may be a reflection of a short study period. Furthermore, decreases in the prevalence of MAP-specific antibodies may not reflect discontinued transmission of MAP in all age groups.
A voluntary, risk-based control program for paratuberculosis in dairy herds was started in 2006 in Denmark. The program does not include non-dairy herds, and the occurrence of Mycobacterium avium subsp. paratuberculosis (MAP) in these herds is unknown. The objective of this study was to establish the prevalence of MAP infected adult non-dairy cattle in Denmark. Serum samples were collected between October, 2008 and January, 2009 from every 6th animal over 24 months of age, sent to slaughter to Danish slaughterhouses from non-dairy herds. The final sample included 2345 cattle of 13 different breeds, with the largest breed group being crossbreds (of unknown breeds) (30%) and three dairy breeds (Danish Holstein, Danish Jersey and Danish Red Cattle) comprising 27% of the samples. The serum samples were tested using a MAP specific antibody ELISA (IDScreen) and positives were defined as the sample-to-positive ratio greater than 0.60. Estimation of the breed-specific apparent prevalences, true prevalences (TP), and true prevalences with a random effect of breed was done in a Bayesian analysis. Information about test sensitivity and specificity were based on literature data and expert information. Regardless of the method of analysis, the estimated prevalences showed similar differences between breeds. The dairy breeds Danish Jersey, Danish Holstein and Danish Red Cattle were ranked highest (i.e. with highest prevalence) (TP medians: 13, 10, and 6, respectively). Combined, the dairy breeds had a significantly higher prevalence than the other breeds, median TP (dairy)=15.7% vs. median TP (non-dairy)=0.8%. For the individual non-dairy breeds, the median estimates were generally higher, illustrating the problems of ranking groups based on relatively small sample sizes.