Johne's happens

Johne's happens

An insidious disease is infecting dairy cattle across Canada. What Atlantic Canada is doing to help its herds.
October 19, 2011

Trudging through a dairy farm to collect manure samples isn’t exactly glamorous work, but the odorous task is starting to have a big impact on the health of dairy cattle in Atlantic Canada — and it will save the dairy industry millions of dollars each year.

Technicians at the University of Prince Edward Island’s (UPEI) Atlantic Veterinary College began collecting these samples this past spring as part of a new study designed to understand and eliminate an insidious disease that affects cattle throughout North America — Johne’s (pronounced YO-neez) disease. Cows suffering from Johne’s do not display many symptoms, so it is hard to detect and diagnose. While generally not fatal, the disease affects the amount of milk cows produce and, as a result, the bottom line of farming operations.

Greg Keefe, professor of dairy health management at UPEI, is spearheading the Atlantic Johne’s Disease Initiative (AJDI), which employs a battery of state-of-the-art tests to detect the presence of the disease on dairy farms throughout the region. The project is funded by the four dairy farmer boards in Atlantic Canada in partnership with the four provincial Agricultural Adaptation Councils and Innovation PEI. The work is supported by Canada Foundation for Innovation (CFI) investments.

The CFI funded several pieces of testing equipment in the AJDI lab. A broth-culture system that Keefe refers to as the “gold standard test” grows bacteria from cow feces to see whether there are traces of the organism that causes Johne’s — a test that takes seven to eight weeks to complete. This technology replaces a less sensitive PCR (polymerase chain-reaction) test that takes about twice as long. PCR is now used primarily as a confirmatory test on broth isolates. Two other testing systems that look for antibodies in blood or milk aren’t as accurate but generate results in 48 hours. Being able to access a variety of results from the four testing systems at different stages is crucial for the AJDI program, says Keefe. “I believe we are the only lab in Canada that is USDA proficiency-tested for all four methods.”

Johne’s disease is contracted by calves soon after birth, but the main symptom — a thickening of the cow’s digestive tract that limits its ability to absorb nutrients — doesn’t begin to appear for three to five years. Cattle that contract Johne’s lose weight and produce less milk, which leads to a loss of revenue — about $2,500 per 50-cow herd per year, according to a 2002 Canadian study. In Canada, with just under a million dairy cows, the total loss is potentially significant. Keefe estimates that anywhere from 25 to 40 percent of dairy herds in Canada are currently infected.

The dairy industry is also concerned about the possibility of disease-based restrictions on cattle movement, as we have seen with other animal health issues in the past decade. “If we don’t take steps now to limit Johne’s,” says Keefe, “other countries may look at placing non-tariff trade barriers on our dairy industry.”

Once evidence of Johne’s disease has been detected in a herd through the initial environmental culture, the AJDI team works with the farmer to develop a control plan that uses risk-management techniques to limit the spread of the disease. Those veterinary visits, says Keefe, are the business end of the program: “That’s where we will see our improvements in herd health, through that one-on-one communication with farmers.”

After an initial control strategy has been successfully implemented, a herd becomes eligible for funding for testing individual cows to refine the plan. So far, about 10 percent of Atlantic Canada’s 700 dairy farms have signed on to the AJDI. Keefe hopes to enroll at least 60 percent over the next couple of years. “This program is already being looked at as a model for managing Johne’s disease in other regions,” he says. “We’ve been getting calls from dairy industry personnel all over North America asking for information about our work.”