Action urged to stop Johne’s disease spread

SASKATOON — Johne’s disease is becoming a bigger concern for cow-calf producers and a veterinarian is urging the industry to get ahead of it now.

Dr. Cheryl Waldner of the Western College of Veterinary Medicine at the University of Saskatchewan said disease risk is increasing as herds consolidate and producers bring in animals.

Johne’s, typically associated with dairy herds, is one of several diseases for which there is no vaccine and no treatment.

Waldner said cow-calf producers, unlike dairy producers, can’t easily take calves off cows right at birth to get clean colostrum into them to minimize transmission.

And infected animals aren’t often detected until they are older.

She said the average lactation number in some dairy herds is only two to three.

“Think of how old some of the cows are that you have in your operations that are still productive that still look good and are still giving you a good calf. Our second and third calvers are just getting started,” she said.

Often, the cows having their fourth to seventh calves are the best.

“We want our cows to get that old and we want them to be healthy,” she told the Saskatchewan Stock Growers Association semi-annual meeting.

Affected animals show extreme rapid weight loss and persistent and smelly diarrhea but don’t have a fever and eat and drink normally. These cows are culled.

Waldner said there are costs either way.

“If we identify them through testing and culling we’ve got a lot of premature culling,” she said. “We’ve got replacement costs … reduced slaughter value, lost gain in the calves, vet testing costs to figure this out and then reputation for seedstock producers. One of the biggest threats to spreading this through the industry is infected bulls coming into your herds.”

Calves are most susceptible within the first six months of life, so keeping their environment as clean as possible helps.

Waldner also noted that the diagnostic tests aren’t perfect, especially on animals younger than two years. There will be occasional false positives.

Cow-calf producers should pay attention because the disease is on the rise. Waldner said 20 years ago less than one percent of cows and about three percent of herds were affected.

Using a definition of at least two positive tests for a herd to be positive, a 2014 survey found up to 1.6 percent of animals and 5.4 percent of herds affected.

The Canadian Cow-Calf Surveillance Network last fall surveyed 180 producers.

“We’ve got data back from 152 so far and we’re up to 1.4 percent positive and 6.6 percent positive herds,” Waldner said.

She said she worries these numbers understate the problem and urged producers to minimize transition within herds by taking measures that can limit Johne’s and other diseases.

“Be really careful about how we manage calving season and contamination,” she said. “Low density calving on grass whenever you can is the solution to so many of the world’s problems. It has some costs in terms of getting cows pregnant again but that’s a story for another day.”

Providing lots of bedding, aiming for clean udders as much as possible and good drainage can all go a long way. Powdered colostrum is the best choice when needed rather than other sources.

Waldner encouraged seedstock producers to start testing so they can advertise as low-risk, and encouraged commercial producers to buy from these low-risk herds.

Producers who have any suspicious animals should test, and a positive test should lead to a whole herd test, and then culling.

The WCVM, with funding from Saskatchewan’s Agriculture Development Fund, is developing a computer tool that will help producers, with their veterinarians, calculate the cost-effectiveness of which test to use and how often.

The SSGA administers the province’s surveillance program funded through the Canadian Agricultural Partnership. Although the program is oversubscribed, Waldner said she has some extra research money that she can use to re-test herds that were done in the past.

“We urgently need to act before we end up in the same situation as the dairy industry,” she added. “I’m using Johne’s as my flagship today but there’s so many other diseases, reproductive diseases, digital dermatitis, some of the causes of calf scours, some of the newer emerging causes of respiratory diseases, that we need to watch out for.”

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