RED DEER – Every pair of rubber boots worn on a dairy farm has the potential to spread Johne’s disease.
“It only takes a teaspoon of manure to infect a calf,” said Herman Barkema of the University of Calgary’s veterinary school.
“If we look at the boots we are wearing on the farm, there is easily a teaspoon there.”
Alberta Milk, Alberta Beef Producers, the universities of Calgary and Alberta and the Alberta government started a Johne’s disease initiative last fall to control the wasting cattle disease.
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Ontario and Quebec have launched similar initiatives that focus on education and improved biosecurity.
The Alberta Livestock and Meat Agency and Alberta Milk contributed $351,000 each to cover program costs.
The disease has been known for at least a century and control programs have existed for 50 years.
However, it continues to spread.
Barkema also researches Crohn’s disease, an inflammatory bowel disease. No solid connection has been found between the two diseases, but some suspect it is transmitted through milk.
“It is not certain, but do we want to take the risk as dairy farmers that there is an association?” he told a regional meeting of Alberta Milk in Red Deer March 29.
Infected cows pass the bacteria in their manure and infect young calves when they suckle or eat straw that came in contact with feces.
However, it is often hard to determine which animal was carrying the disease or when the infection occurred.
Other bacterial diseases, such as E. coli, cryptosporidia and salmonella, are also spread in manure so on-farm cleanliness could also reduce the incidence of those problems in calves. Johne’s causes a thickening of the gut lining, which prevents animals from absorbing carbohydrates or protein from feed. They develop diarrhea, produce less milk, fail to get pregnant and waste away.
Full-blown symptoms take years to appear, but these poor performers are often culled earlier than normal and the farmer never realizes Johne’s was the cause.
“In heifers that are infected, they have a culling rate that is six times higher than heifers that are not infected,” Barkema said.
About 95 percent of infected animals never show clinical signs and an effective detection test isn’t available.
“If you have one clinical cow in the herd, then you have 10 times more cows, at least, that are infected,” Barkema said.
Ten to 20 percent of ELISA tests, which look for antibodies, detect the disease. Fecal cultures are more sensitive, but the disease might still be missed, even in cows with clinical signs.
Herd level tests seem more effective and involve collecting samples from barn alleys, lagoons and the calving area.
Prevalence across Canada is not known, but researchers suspect half the dairy herds have some level of infection. Tests at a processing plant in Moncton, N.B., that handled culled dairy cows showed infection in one in six cows from a slaughter group of 1,000.
Under the Alberta program, a veterinarian does a risk assessment and offers advice on possible changes. There may be 20 recommendations, but farmers are told to select the top three that they are able to make.
Biosecurity measures may include using clean bottles and nipples for calves between feedings and making sure no manure comes in contact with the calves.
Farms may be advised to restrict visitors to the barns and insist on clean boots and clothing. The veterinary school will analyze the risk assessments and learn where failures to control the disease might appear. Ten percent of Alberta’s 595 dairy farms are participating in the program. The goal is for half to join by the end of the year.
Fourteen farms have submitted 84 samples. Eight farms were negative while the rest had varying levels of positive results.
The Ontario program has four components: ongoing educational initiatives, producer-veterinary consultations, optional herd testing and removing highly infected cows.
“(It) is management assistance; it is not a regulatory program,” said Ann Godkin, a provincial veterinarian who works with the Ontario Johne’s Disease education and management assistance program.
Tests are reimbursed at the rate of $8 per cow and in some cases producers may be offered $500 per head to cull infected cows and not sell them to someone else.
Last year, 50,000 cows were tested with 453 testing positive. The program found 168 herds had at least one positive cow. One herd had 28 percent of the cows test positive.
“This is a significant disease and action is needed,” Godkin said.
For more information, visit www.johnes.ca.
