John Kirk, DVM, MPVM

Extension Veterinarian, School of Veterinary Medicine
University of California Davis, Tulare, CA.

As you begin to think about Johne's Disease in your dairy herd, keep in mind that this disease can be prevented and controlled by understanding how it is spread and how it affects cows. Half-heart attempts at control will generally fail, so begin with a total commitment of energy and time. First and foremost, Johne's is a bacterial disease that is spread from infected cows to other cows and young calves in the manure. Additional spread can take place through the colostrum or milk. So you must start by thinking about spread through the manure.

Step 1: Reduce the exposure of newborn calves to manure that may contain the bacteria.

• Calve in a clean dry maternity area. If you are wondering whether it is clean and dry enough, kneel down in the bedding. If your knee comes up wet and covered with manure, the maternity pen needs some work. Frequent cleaning and replacement of bedding is the key.

• Remove the newborn calf from the dam before it has a chance to nurse or even attempt to nurse. Don’t let the calf ingest milk from a manure-covered teat or from other parts of the dam. Ingesting manure greatly increases the risk of Johne's transfer.

• Avoid keeping older cows with diarrhea and weight loss in common maternity pens, as they are the high-risk cows for shedding the Johne's bacteria. Manure from cows with Johne's contains zillions of infective bacteria.

• Have a separate maternity pen and another hospital pen to reduce exposure to newborn calves.

Step 2: Provide clean feed for young stock and mature animals.

• Do not feed potentially contaminated feed from adult cows, including refused feed, to young stock. The risk of infection is greatest in the youngest animals meaning that a smaller dose of Johne's bacteria will infect a young calf compared to a yearling.

• Use separate equipment to handle feed and manure. The same tractor should not be used to scrap a cow alley and then be used to push up feed. Manure is the source of infection.

• Reduce to a minimum the crossing of cow alleys and feed alley with vehicles. Again, moving manure from one place to another is the same as moving the Johne's bacteria from one place to another.

• Keep adult cows and young stock in separate pastures. Provide separate sources of feed and water.

Step 3: Provide clean water for young and mature animals.

• Supply clean water to all animals.

• Use trough and individual Waterers.

• Restrict run-off from pens or corrals particularly run-offs from adult animals that may enter locations where young stock is housed.

Step 4: Keep manure from mature stock from contacting the young stock.

• Raise young stock in separate areas from older animals to prevent exposure of young animals to the potential of Johne's bacteria in the old stock manure.

• Prevent manure run-off from mature animals from reaching the young stock. Remember manure and water both run downhill, so put the young stock uphill from the older animals.

The next area for consideration is the spread of Johne's Disease through the colostrum and milk. By following these steps, you will also be reducing the risk of several other calf-hood diseases.

Step 1: Feed "low risk" colostrum.

• Use only colostrum from healthy cows that were negative on a recent Johne's test.

• Give the calf only colostrum from its dam…. no pooling. Pooling will increase the chances of infecting many calves from a single infected dam.

• Save colostrum from "low risk" cows by freezing or refrigerating.

• Consider using colostrum supplements particularly if your herd is highly infected.

Step 2: Feed "low risk" milk.

• Feed a milk replacer instead of unknown status milk.

• Pasteurize milk or use milk from only cows with recent negative Johne's test.

• Thoroughly clean the udder and teats before collection of milk for calf feeding.

The final area of consideration is the management of infected cows to reduce the chances of spreading infection to other herd-mates and young stock. Again, many of these suggestions should be included in any herd biosecurity program.

Step 1: Identify and remove clinical and late stage animals as soon as possible.

• Watch for and confirm the diagnosis of Johne's-suspects early.

• Test-positive cows should be culled or at the very least segregated from the maternity areas and young stock.

• Colostrum from test-positive cows should not be fed to any calves.

• Calves born to test-positive cows are at higher risk for Johne's disease so consideration should be given to selling them rather than keeping them for herd replacements.

Step 2: Test to manage subclinical infections and define your herd status.

• Test a portion of the herd to determine the herd status. Testing as few as 30 adult cows can give an accurate prediction of the level of herd infection.

• Cull, segregate or manage the test-positive animals to reduce exposure to other animals in the herd, particularly the young stock.

• Develop a plan with your veterinarian for testing of adult cows on a regular basis.

Step 3: Be aware of the risk when adding new animals to the herd.

• Ask your veterinarian about the risk from adding cows with Johne's, salmonella, Strep ag, Staph aureus, BVD, mycoplasmas and hair heel warts.

• Consider pre-testing animals before bringing them into your herd.

• Isolate all newly arrived animals before mixing them with your herd. Delay mixing until you have tested for high-risk diseases such as Johne's.

This may seem like an overwhelming list of things to do just to control Johne's Disease. By working with your veterinarian, you can break the list down to parts that can be managed. Over time you can develop a plan that will greatly reduce the risk of Johne's Disease in your herd. Ask your veterinarian to start working on a plan today.