Remember that the infection can spread from one ruminant species to another, so assess the risk of infection for all your young ruminant animals.
A computer simulation model illustrates that faster Johne's control can be accomplished by changing both bison rearing procedures and testing the adult herd to identify and cull the infectious animals. Of these two basic strategies, changing cow management to limit the chance of calves becoming infected (swallowing the organism) is the most important.
. . . manure management
The most MAP bacteria excreted by infected ruminants are in the feces (manure). Farm sanitation and control over where manure goes on a farm are critical to control of Johne's disease. Because of the susceptibility of calves to MAP infection, it is important to keep them well away from adult bison manure that may harbor the infection at least for the first 6 months of life, the "window" of maximum susceptibility.
Calves should be born in a clean dry environment with minimal fecal contamination. Individual birthing pens or paddocks are optimal but if not feasible, you may establish test-negative and test-positive pens (you could test all your adult animals a few months ahead of time to have this test information available). Then try to establish an area outside the pen free of adult manure contamination (“the safe zone”) for calves from test-negative dams.
Manure contamination of water supplies must be avoided to limit spread of the infection, particularly ponds or streams that young animals can drink from. If you use water troughs, when cleaning them remove the sediment at the bottom and dump it away from where animals might graze – MAP apparently survives for a long time in this substrate.
Pasture contamination with MAP is also important as a means of infection transmission, but it is less so than other modes of transmission and far more difficult to control. Till contaminated pastures and wait for time and environmental conditions (repeated changes in temperature, minimize shaded soil by cutting grass/crops/shrubs) to kill off MAP on fields. While a majority of the organisms die within three months, a small population can remain for up to a year. Put off stocking contaminated pasture with young animals as long as feasible. Be aware of what the pasture was used for before putting your youngstock on the premises. Farmed bison are often grazed on fields that had been used for dairy cattle - MAP infection is a common problem for dairies.
Read about survival of MAP in the environment in the "Biology of MAP" section of this site.
Many animals infected with MAP will excrete the bacterium in their milk. This happens most often in animals showing clinical signs of Johne's disease, but also occurs in infected animals that still appear healthy.
If you need to bottle-feed a calf, use pasteurized milk or milk replacer. A recent study saw no difference in the number of new cases of Johne’s disease arising in dairy herds (cattle) between those that pasteurized and those that used milk replacer. Recommended protocols: 145°F (63°C) for 30 minutes for batch pasteurization, or 162°F (72°C) for 15 seconds for flash pasteurization. The milk should be stirred or otherwise in motion to ensure even heat distribution.) Pasteurization kills virtually all MAP that may contaminate raw milk as well as other viral and bacterial agents that could affect the calf’s health.
Colostrum, the antibody-rich milk produced in the first few days after giving birth, also can contain MAP. Because colostrum is critical to the health and survival of newborns, feeding colostrum must be done.
While these articles focus on cattle, they are excellent sources of information and can be found in the "Articles and Brochures" section of this website. Three articles in particular to read are:
MAP infections can be transmitted from mothers to offspring by contact with the mother's infected feces, through infected colostrum or milk from the mother, or across the placenta into the fetus before the calf is born. Depending on the extent to which manure management and milk/colostrum management recommendations listed above can be implemented, there is a moderate to high probability that calves born to MAP-infected mothers will acquire the infection. Consequently, on a case by case basis, it may be wise to cull offspring born to infected mothers. If not culled, it may take two or more years to determine if the young animal became infected, and this will be time lost in pursuit of control or eradication of the MAP in the herd.