April 24, 2020

Signs, Symptoms, Prevention, and Control

Johne’s disease in dairy cattle is more common than you might think! Johne’s disease (JD) is caused by millions of tiny bacteria that are invisible to the naked eye. These bacteria are called MAP, and they are mainly spread through the manure of infected animals. Unfortunately, we don’t have cost-effective treatments or vaccines to help protect cows from infection. Most importantly, infected animals often don’t show signs or symptoms for years, even though they can infect others during this time. This is why JD is known as an “iceberg disease”; the few cows you see with symptoms are just the tip of the iceberg (there are likely many more infected animals in your herd you can’t see!). Actually, less than 5% of animals infected with JD actually show any symptoms; that’s a lot of sick cows that you can’t see! And what is scary, is that these animals will look healthy and will often be absent of symptoms, but they are actually spreading the disease to other animals (this is called the “subclinical” phase).

 

This disease can be spread between farms when an infected cow is bought at auction. Typically, a cow becomes infected with JD as a young calf. The calf may drink contaminated colostrum or milk or it has a “manure meal” (eats manure or suckles from a teat that has manure on it) from an infected animal. Symptoms that may eventually appear may include decreased in milk production, diarrhea, or weight loss.   As treatment of infected cows is not a viable option, prevention and control of JD needs to be your focus. Things you can do to prevent JD that are low cost and easy to implement include:

  • Ensure lots of clean bedding in calving areas and quick removal of manure
  • Have separate calving pens to reduce contamination
  • Use small portable calf pens to keep calves away from their dam’s manure
  • Have a “sick pen” strictly for cows who test JD positive or show symptoms
  • Regularly test your herd for JD (talk to your vet about the best tests for you)
  • Freeze colostrum from healthy cows (JD negative cows) to feed to calves who may be born from an infected cow (JD positive cows)
  • Don’t pool colostrum, as infected colostrum could contaminate all of it
  • Have a second bucket for skid steer; one for feed and one for manure

As you can see, these changes are about preventing calves from coming into contact with MAP. Keeping your young stock away from manure and contaminated milk and colostrum is never a bad thing; it will help prevent a variety of important illnesses!   Overall, it is important to consider what changes can be made on your farm. You should talk to your veterinarian to develop a JD action plan to test, treat, and prevent JD on your farm. Calving area cleanliness and good calf management are the most important steps to preventing the spread of Johne’s Disease.

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Agricultural Communications &
Epidemiological Research

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