Dairy: Risk assessment program for Johne's disease can yield other benefits

Thursday, December 3, 2009

Best to deal with the disease now, while prevalence is low, argues the province's veterinarian. And risk assessments already done have helped get to the bottom of other problems as well

by SUSAN MANN

When Ontario's dairy farmers complete the risk assessment as part of a new Johne's disease education and management assistance program starting in January, they'll learn a lot more about calf management.

"There are other problems that can be fixed with a Johne's risk assessment," says Dr. Ann Godkin, Ontario agriculture ministry veterinarian specializing in disease prevention. And that's just one of the reasons she says farmers should participate in the voluntary Johne's Disease Education and Management Assistance program.

In Ontario, it's estimated that 30 to 50 per cent of dairy herds have one infected cow. Cows infected by Johne's disease produce less milk even if they don't show signs of sickness. Ron Versteeg, vice-chair of Dairy Farmers of Ontario (DFO), says that Johne's is incurable but preventable. Thus, it is in producers' best interests "to deal with it now while it's still a small problem." 

The program has three elements:
•    A veterinarian's on-farm risk assessment – a questionnaire to assess calf management, along with recommendations based on the assessment;
•    Cow testing to classify herds as negative, low, medium or high prevalence for Johne's infection;
•    Culling of high-risk cows to prevent disease spread.

The major objective of the risk assessment is to find and stop all the ways the organism in cow manure gets into the mouths of calves and starts a new infection, Dr. Godkin says. Other diseases transmitted that same way, such as calf diarrhea, can be reduced if farmers follow all the recommended practices for Johne's prevention.

"If you are feeding calves well, making sure they get colostrum and adequate amounts of milk, then you can reduce respiratory disease as well," she explains.

Dr. Jamie Hobson, president of the Ontario Association of Bovine Practitioners, says the risk assessments he has done have led to discussions about getting to the bottom of other problems in addition to Johne's.

He says reaction to the upcoming program from farmer clients is mixed. Most agree it's needed, but they think it's going to be more work for them. "They need to see that the effort is going to benefit them in more ways than just the Johne's prevention and the market preservation."  

Another reason to participate is if a farmer has never tested the herd for Johne's before because of the cost. "This is a chance to do it essentially for free," Dr. Godkin says.
Farmers can be reimbursed $8 per cow tested as part of the program. Participants will be given a six-week period to have all lactating cows in their herds tested. "That's to ensure we don't flood the lab all at one time,"

Dr. Godkin says.  The times will be allotted based on DFO dairy producer committee regions.

But farmers will have to pay some of the costs for the program, such as the herd veterinarian's on-farm risk assessment, which will be required annually. The cost will depend on the time required and the vet's fee. Dr. Godkin says for herds undergoing a first-time assessment, the process should take 45 minutes to one hour.

Farmers should also participate because testing to prove their herd's status may interest animal buyers, she notes.

The program has funding to test 75 per cent of all the herds in Ontario.
And if that many herds are tested, Dr. Godkin says, this will give a much better idea of Ontario's infection rate plus the patterns and trends of the disease over time.    

It's unlikely the program will result in eradicating Johne's because the organism causing it survives in other species and potentially can survive in the environment, she says. In addition, it's very hard to identify all infected animals at one time.

"We do believe we can push it down to very, very low prevalence," she adds, noting that, in most herds now, the prevalence is very low. "We just have to ensure people understand why they have low prevalence and keep on doing the things that keep them that way."

Information about the program will be available through DFO's magazine, and a website that is being set up. Farmers can also call their veterinarian, or Dr. Godkin at (519) 846-3409 or Jocelyn Jansen at (519) 846-3414. BF