Management practices associated with Johne's bulk tank milk ELISA positivity

Area of Science:

• Veterinary Medicine
• Animal Health
• Epidemiology

Background:

• Johne's disease (JD) is a chronic infectious disease caused by Mycobacterium avium ssp. paratuberculosis.
• Control strategies typically involve culling infected animals and minimizing pathogen exposure for young stock.
• Ontario, Canada, implemented a voluntary JD control program from 2010-2013, involving whole-herd testing and risk assessment.

Purpose of the Study:

• To assess the prevalence of JD high-risk herds in Ontario after a voluntary control program.
• To identify management factors associated with successful JD control in dairy farms.
• To evaluate the effectiveness of management practices beyond the maternity area.

Main Methods:

• Province-wide bulk tank milk (BTM) testing using ELISA to identify JD high-risk herds in 2013 and 2017.
• Administration of a JD risk assessment tool evaluating 5 management areas on 180 dairy farms in 2019.
• Logistic regression analysis to correlate management factors with JD control outcomes.

Main Results:

• BTM testing showed an increase in JD high-risk herds from 46% in 2013 to 71% in 2017.
• Farm cleanliness scores for weaned and bred heifers were significantly associated with JD control success.
• Exposure to mature cow manure was also linked to unsuccessful JD control efforts.

Conclusions:

• Management of the maternity area is important, but JD control extends beyond this initial stage.
• Maintaining cleanliness and minimizing manure exposure for older heifers is critical for JD control.
• Continuous, rigorous management practices throughout a calf's development are essential for effective Johne's disease control.