MADISON, Wis. — A Wisconsin field trial has proven that a Johne’s disease control program is both effective and affordable.
The disease can cause body wasting and chronic diarrhea, but not all cattle show these clinical signs, which creates a dilemma for dairy producers.
Which cows should be removed or isolated from the herd? It’s prohibitively expensive to do a fecal culture or polymerase chain reaction test on each cow to check for Johne’s disease.
For the past six years, the University of Wisconsin-Madison School of Veterinary Medicine’s Mike Collins, in cooperation with the Wisconsin Milk Marketing Board, USDA and the Wisconsin Department of Agriculture, Trade and Consumer Protection, has conducted a trial on nine Wisconsin dairy herds ranging from 72 to 1,400 cows.
The results are promising. Based purely on ELISA tests of blood samples taken annually as a cow enters milk production, producers have culled strongly positive cows and managed mildly positive cows differently.
By the time heifers reached their first lactation, the incidence of Johne’s disease was significantly lower than expected, proving that good management coupled with use of a low cost, less sensitive test was working.
The ELISA blood tests are less than $10 per cow per year. And the cost will become even more affordable if current studies reveal the same results are possible by testing milk samples as opposed to blood.
In addition, the practices recommended for Johne’s control are also effective at controlling other pathogens that are transmitted from cows to calves via fecal-oral route, resulting in healthier calves.
Managing mildly positive cows in a way that lessens chances for transmission of the disease is part of the equation; it keeps the cow producing farm income but limits her negative impact on the farm caused by spreading Johne’s disease.
This includes keeping infected animals away from the “clean” maternity pen, ensuring calves get colostrum only from ELISA-negative cows, housing calves away from adults and feeding calves only pasteurized milk.
This is translational research; laboratory research being used in the field to solve important problems for Wisconsin’s dairy industry.
Studies on the nine Wisconsin dairy farms continue to evaluate new tests developed at the University of Wisconsin and application of the ELISA to milk samples.