Milk Producer - March 2010 - (Page 38)

APPLIEDSCIENCE Sébastien Buczinski, Jean-Philippe Roy, Gilles Fecteau, Pascale Aubry, Michel Bigras-Poulin, Marie Archambault, Olivia Labrecque, France Sylvestre and Mado Fortin Effective tool Risk factor assessment questionnaires help paint a clear picture of the potential for Johne’s disease in your herd hat detailed risk factor questionnaire your veterinarian uses in a Johne’s disease prevention and control program has proven to be an effective tool. Before your herd status is known through testing, a completed questionnaire can indicate the likelihood of the disease’s presence. Diagnosing dairy cattle infected with Mycobacterium avium ssp paratuberculosis (MAP), which causes Johne’s disease, is difficult. However, several risk factors have been identified in infected herds. These factors mainly relate to the potential for young animals to ingest feces and the farm environment’s pathogen load. Identifying these factors led to the creation of the questionnaire vets currently use for farms participating in Quebec’s Voluntary Johne’s Disease Prevention and Control Program. We did a study to determine whether questionnaire results accurately reflect the farm’s initial status as a MAP-infected or uninfected herd. The findings will be used to determine whether certain questions are more important for disease detection in herds and to improve the questionnaire. The study was conducted by the faculty of veterinary medicine at the Université de Montréal and the Laboratoire d’épidémiologie animale du Québec (the provincial laboratory dealing with animal disease transmission and control). With the help of veterinarians, 58 Quebec dairy herds—29 presumably healthy and 29 presumably infected—were select38 | March 2010 | MilkPRODUCER Calf care is considered a major part of Johne’s control programs. T ed and analysed in different regions of the province (Montérégie, Centredu-Québec, Lower St. Lawrence, Eastern Townships, Mauricie). Scores determined Based on the available data, half of the herds were classified as infected and the other half as disease-free. At each farm, a vet completed the risk assessment form in co-operation with the producer. Individual scores, measured by percentage, were determined for the questionnaire’s different subsections: • calving area; • nursing heifer calves; • weaned heifer calves; • heifers over 12 months of age; • cows. Vets then calculated an overall score for the farm. To confirm each herd’s disease status, a fecal culture and an ELISA blood test were performed for 30 randomly selected cows over three years of age. Then, the overall questionnaire score for each herd was compared with test results used to classify herd status— infected or uninfected—to check how well they correlated. Of the 29 presumably infected herds, four had negative test results. Seven of the 29 presumably healthy herds were found to be infected with at least one positive test. The farms were reclassified for analysis. In the analysis of the different questionnaire subsections, a significant difference was observed in relation to the management of pregnant or breeding-age heifers and cows. More specifically, higher scores were obtained in these categories for infected herds compared with uninfected herds. As a rule, the higher the score value, the greater the risk. Infected herds score higher Overall questionnaire scores generally were higher for infected herds than for disease-free herds. While the difference was not statistically significant in relation to the herd’s final status—based on individual tests—it was significant when the herd’s presumed disease status was taken into account. When herd status is unknown, the

Table of Contents for the Digital Edition of Milk Producer - March 2010

Milk Producer - March 2010
Contents
Editor's Notes
DFO Chair's Message
Provincial Perspectives
Dairy Update
DFC Policy
Farm Finance
DFC Promotion
Heating With Cow Power
Processor Spotlight
Issues Update
Research
Applied Science
Ruminations
Markets
New 'N' Noted
Back Forty

Milk Producer - March 2010