Dairy, beef producers can better manage Johne’s disease by focusing on calves
“Focus on the calf” is the simple and straightforward take-home message for all dairy and beef producers for controlling Johne’s disease in their herds. This was the conclusion of Michigan State University (MSU) researchers and Extension specialists after conducting field research and evaluating Johne’s disease control strategies for close to a decade in Michigan herds as part of the Michigan Johne’s Disease Control Demonstration Project. The objective of the work was to identify which management practices are the most effective at controlling the spread of Johne’s disease.
MSU AgBioResearch scientist Dan Grooms, professor in the MSU College of Veterinary Medicine and lead researcher on the project, summarized the findings in four words: focus on the calf.
“It sounds too simple, but if we can simply reduce the risk of calves becoming exposed to the bacterium that causes Johne’s disease, then we can make significant progress in reducing the impact of the disease on both dairy and beef operations,” he said.
Johne’s disease is a contagious and untreatable disease caused by the bacterium Mycobacterium paratuberculosis, or MAP, that affects primarily the small intestine of ruminants. Johne’s disease symptoms include weight loss and diarrhea with a normal appetite. Though infection typically occurs in calves, animals generally don’t express clinical signs of the disease until later in life.
Grooms explained that the goals of the project were to evaluate the effectiveness of Johne’s disease control strategies, develop new knowledge about control strategies through field research studies, develop education resources and promote the Michigan Voluntary Johne’s Disease Control Program. The Michigan Department of Agriculture and Rural Development (MDARD) and the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) administer the program.
Nine herds – one beef operation and eight dairy herds – were enrolled in the Michigan project. Selected farms represented a variety of management styles and were located across the state. Farms were enrolled in the project between 2002 and 2005 and participated in the program for four to seven years.
Each herd underwent whole-herd testing to measure baseline levels of Johne’s disease infection. From there, a disease risk assessment was conducted, and management practices were put in place to help control on-farm spread of the disease.
All of the herds participating in the project tested positive for Johne’s; the percentage of cows infected in each herd ranged from 6 percent to 14 percent.
“Each of the nine herds – like the majority of dairy and beef operations in the state – was infected with Johne’s [disease] at the time of enrollment,” Grooms said. “At the end of the project, the farms had reduced the prevalence of Johne’s disease in their herds and the number of cattle detected with clinical signs of the disease, and improved the overall herd health.”
What was the most compelling piece of evidence collected by researchers supporting the recommendation to focus on calf management practices to reduce the incidence of Johne’s disease?
“In every herd that participated in the project, significant changes were made to how the calves were managed, and the incidence of Johne’s was reduced significantly,” Grooms said. “By focusing resources and efforts on reducing MAP transmission from older animals to young calves, producers can effectively manage Johne’s disease and reduce its impact on farms.”
Grooms said that findings from this work will have a far-reaching and positive effect on the future of the beef and dairy industries.
“The program has provided background for educating producers on the positive correlation between implementing effective management decisions to control Johne’s disease in their operations and the profitability of their businesses and overall improved animal welfare,” he said.
The Michigan Johne’s Disease Control Demonstration Project was a partnership between the MSU College of Veterinary Medicine, the MSU Diagnostic Center for Population and Animal Health, MSU Extension, MDARD and the USDA, in collaboration with nine Michigan veterinary clinics. Findings from the Michigan farms involved in the study were pooled with data collected from 17 other states as part of a multi-state project, the National Johne’s Disease Control Demonstration Project.
Results from field-based research studies associated with the project are available in hard copy in the publication “The Michigan Johne’s Disease Control Demonstration Project: Research Findings, Lessons Learned, and Producers’ Perspectives,” or as a downloadable document at http://cvm.msu.edu/johnes.
Photo: MSU AgBioResearch scientist, Dan Grooms
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