Johne’s Disease

Johne’s disease is a chronic infectious disease of the small intestine caused by Mycobacterium avium subspecies paratuberculosis (MAP) which causes a thickening and breakdown of the intestine’s lining. The thickening of the intestine prevents nutrient absorption, resulting in diarrhea and weight loss despite a health appetite. Johne’s is introduced to a herd when a producer unknowingly purchases an infected, but healthy looking animal. The new animal quietly spreads the bacteria into the environmental infecting other animals. Johne’s works in an “Iceberg Phenomenon”. 1 clinical cow only represents the tip of the iceberg. Typically for every cow showing clinical signs, 15-25 other cows are likely infected. The National Animal Health Monitoring System Dairy 2007 study indicated that 68.1 % of U. S. dairy operations are infected with MAP.

What does Johne’s Disease cost you?

The National Animal Health Monitoring System 1996 study found that:

n Dairy herds with a low Johne’s disease clinical cull rate lost an average $40 per cow.

n Dairy herds with a high Johne’s disease clinical cull rate lost an average of $227 per cow

Losses are primarily attributed to reduced milk production and premature culling, but losses in milk component value and reproductive efficiency are also significant.

Considering the economic losses of Johne’s disease, it may be time to evaluate your herd’s risk level Minnesota DHIA offers the Milk ELISA Johne’s test to all producers using the regular testday milk sample. Results are back to you typically in less than one week and can be electronically imported in to Dairy Comp 305 or Scout management software. The Milk ELISA is approved by the Board of Animal Health for the Minnesota Voluntary Johne’s Disease Control Program. The cost is $6 per sample. It is recommended you work with your local veterinarian to develop the appropriate testing plan for your herd and how to manage your herd’s risk. Most Johne’s management plans consist of a testing for the disease and making a few changes in management to reduce spreading the disease.

How can you reduce the spread of Johne’s Disease?

Newborn calves are the most susceptible to infection of Johne’s. They can become infected by ingesting the bacteria on manure-covered teats or from colostrum or milk from infected cows. Unborn calves can also become infected in utero if their mothers are infected. Basic prevention and control strategies include: 

n Calves should be born in a clean environment.

n Reduce the newborns’ exposure to manure from adult animals. (For dairies, separate newborns when possible.)

n Avoid manure contamination of feed by using feed bunks and not using the same equipment to handle feed and move manure.

n Avoid manure contamination of water sources where animals drink.

n For natural colostrum needs of newborn animals, use colostrum from Johne’s negative animals.

n Do not pool colostrum.

n For dairies: Avoid natural nursing and milk feeding whenever possible. Feed an artificial milk replacer or pasteurized milk instead of raw milk to supply the needs of newborns. Never feed unpasteurized pooled milk or waste milk.

n Thoroughly clean the udder and teats before collection of the colostrum to avoid manure contamination.

n Because MAP can survive up to a year in the environment, pastures that have become contaminated should be tilled or grazed using non-replacement feeder cattle if possible.

n Identify all animals kept for the herd. Identify and remove, or keep separate, all test positive animals.

n Prevent infection from spreading by culling, or separating, offspring of infected mothers as soon as possible.

n If purchasing herd additions, try to buy from low-risk herds. Some herds are enrolled in the Voluntary Bovine Johne’s Disease Control Program or an equivalent State program to help identify their herd as low risk.

Not sure if Johne’s disease is a problem in your herd?

You can work with a your veterinarian or a regional Veterinary with the Board of Animal Heath to perform a Risk Assessment of your dairy to see if contracting Johne’s disease into your herd is a possibility and how quickly it would spread. You can contact the Board of Animal Health at 651-201-6804 for a veterinarian near you. For a complete list of all the herds that are part of the Minnesota Test Negative Status Program for Johne’s, follow this link http://mnlists.bah.state.mn.us/johnesneg/PREMISES_list.asp .