As buyers become more aware of the disease, they may demand to know the Johne s status of any breeding stock they buy. Besides these direct costs and the expense associated with controlling the disease in infected herds, dairy producers who sell breeding stock also face the same liability issues described for beef producers. Johne s affects ruminant animals and has been found in numerous species of ruminants. This disease should be considered a whole-herd challenge, as much as an individual animal problem. Affected cattle usually don t have a fever.
Some infected animals appear weak and unthrifty, while others only have chronic diarrhea.
In an infected herd, noticeable signs commonly begin following a stressful event like calving. If you don t see symptoms of the disease, it doesn t mean animals in your herd don t have it it is easy to miss signs of the disease, unless you investigate whether it s there, specifically. As the body works to eliminate the bacteria, immune response causes the intestinal lining to thicken, which prevents normal function and leads to poor nutrient absorption and eventual diarrhea. Within herd, the most common source of infection is feces, or manure. As well, studies suggest 36 percent of cows in later stages of the disease could transmit Johne s microbes to calves, via colostrums and milk.