• Johne’s disease, caused by Mycobacterium avium ssp paratuberculosisis (MAP) can result in 25kg reduction in weaning weights in calves from dams having a strongly positive blood test, relative to calves from dams having a negative blood test. It will also cause increased and early culling of infected animals with weight loss and diarrhea.
• Disease in infected cattle has a long silent or “latent” period. Infected cows will shed the organism before the show clinical signs.
• Once an animal is infected there is no cure, and no vaccine is available in Canada. Infected animals eventually become clinically ill with severe weight loss and will die. Cows with early infections also cost producers in reduced weaning weights. Prevention is the best strategy.