Voluntary Johne’s control coming

By Frances Anderson
Ontario Dairy Farmer magazine
This news story originally appeared on http://www.ontariofarmer.com, December 3, 2002

The program will in place likely by January, with a testing protocol being created

A voluntary, nation-wide program to identify and control Johne’s in dairy and beef cattle could be in place as early as January 2003, Gord Coukell told Ontario milk producers at their fall policy conference.

Coukell, who is chairman of the Dairy Farmers of Ontario, represents the Dairy Farmers of Canada on the Canadian Animal Health Coalition’s working committee for Johnes Disease.

The committee approved final details of the control program proposal recently in Winnipeg and will present it to the coalition in December. However, Coukell said they also agreed there should be another national forum before the program is introduced, so it won’t likely be launched until mid-2003.

“We have accepted the concept that it would be good to have a national, but voluntary, control program, sanctioned by the Canadian Food Inspection Agency and delivered by veterinarians, with commodity groups to deliver awareness and best management practices,” Coukell said.

The program will be national because the country’s Johne’s status affects livestock exports, and because of the ease of administration. It will be very similar to the volunteer program initiated a year ago in Alberta, Coukell said.

The United States, Australia and the Netherlands all have national voluntary plans and Japan is considering excluding all imports from countries without a national Johne’s control plan.

The Canadian proposal has three components: promoting producer awareness of best management practices, herd testing for Johne’s, and disease control and reduction. “Herd certification is the only way to control the disease. I don’t know of any place eradication is being looked at,” said Coukell.

The provincial veterinary services are committed to testing. “Now we are working to see how much money the government will provide,” Coukell said.

The committee is looking for $165,000 in startup funding for dairy and beef groups to launch the program, as well as $20,000 in annual maintenance costs. The industry proposes to share costs equally with the government

Control requires testing 

“The tests are not as reliable as we would like,” Coukell acknowledged. However, he said, “they are as good as the tests used for brucellosis” and that’s why he’s able to support the proposed control program.

The American program recommends testing all cows at the end of lactation, but they have larger herds, said Coukell. He expects that a random sample of animals three years old and beyond will be sufficient. As the animals get older, the tests become more reliable.

There will probably be a combination of tests being used. At this point in time, either blood or fecal samples are approved. Testing 30 cows in herds of less than 100 animals, 40 cows in herd of 100 to 200, and 50 cows in the herds of more than 200 will give a representative sample.

It may be possible to pool five blood samples in one culture and pool manure samples from five to 10 cows to reduce costs without compromising results. Producers’ costs will likely range from $210 to $350 for testing 30 to 50 animals.

Dairy Herd Improvement has been investigating the possibility of testing milk samples for Johnes. “Initially there was a significant amount of unreliability,” said DHI chairman Jim Jenkins. So the research with the University of Guelph is ongoing.

Researchers are also working on tests for skin and hair samples, said Coukell. “We haven’t pinned down the criteria for the herd status program yet,” said Coukell. Tested herds will be classified as low, medium and high prevalence herds and herds will be able to move from level one through four as they test negative for Johnes over time.

It’s not clear how prevalent Johne’s is in Ontario. A sample drawn from the Sentinel herds, which is not random, suggests that 2.2 per cent of cows and 37 per cent of the herds in the province will have Johne’s. Probably 49 per cent of herds in Canada have at least one Johne’s positive cow.

The prevalence in the U.S. was initially estimated at 22 per cent herds, then increased to 40 per cent as testing results came in.

Bacterium persistent  

The disease is spreading because of the way herds are managed, and the way cattle are moved between farms, and between countries. Managing cattle in large groups, increases the incidence of infections and the practice of feeding surplus milk to calves enables one cow to infect many others.

Johne’s disease, or paratuberculosis is a very persistent mycobacterium that can exist in dairy herds for years without any animals developing a clinical case. When the bacterium becomes active, the animal suffers diarrhea and weight loss. The organism can be transmitted in utero, in colostrum, in milk and in feces. It also travels in feed and water.

“The bacteria can survive 246 days in sunlight, so spreading manure on the ground is not an effective way of killing this bacteria,” Coukell told producers. And “we need to make sure we keep manure on the land, because in water, it will live up to 455 days.”

“We may have trouble killing it in water, so it’s better to rely on prevention than deal with it after the fact.”

Hygiene is critical

“Best management practices are where you can make the biggest difference on your farm,” Coukell explained during a slide presentation. Attention to hygiene is critical to stop new infection. “The goal is to interrupt transmission.”

Do some testing and isolate the cows that are positive. Then, remove calves from cows while they are still wet, before they begin nursing. “It won’t make the animal welfare people happy, but it may be the best action,” said Coukell. Then, ensure the calf gets four quarts of high quality colostrum from a negative-test cow. Another alternative is to feed only pasteurized milk.

Clean feed and water is also critical. In fact, contaminated feed may be one of the main vehicles for transmission of Johnes. “You can’t scrape the yard with a bucket and then go get a load of feed.” Separation of these functions is critical.

So far, Wisconsin is the only state that identifies positive test animals. There, the vet punches a ‘J’ in the ear and the cow may only be sold for slaughter or with a note that identifies it as a positive carrier.

“One of the things that’s not well recognized is that animals testing positive for Johne’s should be sent to the renderers,” said Coukell. The bacterium travels in the blood, and crosses to the meat and milk as well.

Risk to humans 

The consequences of human exposure are still unclear. “The link to human health is through Crohns’ disease (which impairs the intestine’s ability to absorb food), but there’s as many reports that say there’s no link as say there is,” said Coukell. He was inclined to believe that Crohns and Johnes were linked until recently, when a researcher from the United Kingdom presented contrary evidence at seminars in Ottawa and Guelph.

“As a consumer, I find this (link) scary,” a representative from the Consumers Association of Canada told delegates to the DFO conference. “As a former cattleman, I know the rendering plant is not the first place your take your cattle. Is there discussion about making this a reportable disease?” she asked.

“That’s a question for the CFIA. Our view is that if you’re going to test to identify these animals, then the animal needs to be identified.”

Coukell assured the group, “the University of Guelph has tested pasteurized milk and there’s no evidence of it. The milk supply is totally safe, and as far as we’re aware of, the meat supply is as well - as long as you don’t eat raw meat. “

“Johnes is prevalent. It appears to be spreading In many peoples’ view, prevention possible. Control is possible.”

“The farm is the critical control point,” Coukell said, and it makes economic sense to control Johnes because it is a production-limiting disease.

Sidebar

No discussion about making Johnes reportable

There’s little discussion of making Johne’s Disease reportable to the Canadian Food Inspection Agency.

The main reason it’s not reportable is that the link to human health has not been clearly established,” says CFIA veterinarian Jim Clark. The secondary reason it’s not reportable is that it’s so ubiquitous.

“Our organization basically represents animal health concerns,” said Clark. And while Johne’s is a production limiting disease, it’s so widespread that the cost of introducing an eradication program, and compensating farmers for slaughtering Johne’s positive animals “would be unbelievably high,” said Clark.

If Health Canada, which represents human health interests, determined that Johne’s represented a human health hazard, then the CFIA would likely have to develop a program. But that risk has not be clearly demonstrated.

“A number of years ago, we had a voluntary Johne’s control program, but the industry chose not become involved,” Clark said. The incidence at farms which did test for Johne’s proved to be high enough, that the farmers dropped out of the program because it would have cost them too much to slaughter Johne’s carriers.

Clark attributes the cattle industry’s current initiative to introduce a voluntary Johne’s control program to worldwide concerns about the human health link with Crohn’s.