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|Johne’s disease is an increasing problem – Should manure be applied to forages?|
|Written by Christine Brown|
|Wednesday, 11 November 2009 08:18|
Johne’s disease is a persistent and debilitating bacterial disease that affects the intestines of ruminant animals.
The disease is especially problematic in dairy herds, where many cattle can be infected, but only a small percentage of animals (less than 5 percent) show the clinical signs of chronic diarrhea and extreme weight loss. These cows also experience decreased milk production.
Infected cattle, even those not showing sickness, may shed the bacteria in manure. Animal susceptibility to infection Johne’s disease is caused by Mycobacterium avium paratuberculosis (MAP).
Calves, especially those under six months of age, are most susceptible to infection. Animals under stress are also more susceptible than healthy cattle.
The common routes of infection are via ingestion of colostrum or milk contaminated by infected cows. For this reason, Johne’s prevention strategies revolve around calf management and herd testing.
Infection can also occur when feed contaminated with manure containing the MAP pathogen is eaten, particularly by youngstock. For this reason, manure application to forages is a potential source of infection.
Survival of the disease bacteria in the environment
Factors that reduce the survival of the bacteria can also help in better managing manure applied to forages.
*Table omitted but is available upon request to
—Excerpts from OMAFRA Crop Talk, June 2009