A study of infectious disease in cattle shows Canada has a healthy beef herd.
It began measuring the incidence of bovine viral diarrhea, bovine leukosis virus, neospora caninum and Johne’s disease in 179 herds in 2003. The diseases were selected because they are known to exist in Canada and are chronic conditions with economic or trade implications.
“It is a good news story on the beef industry herds that we had a fairly low prevalence to leukosis and Johne’s that might become trade issues at some point,” said John Campbell of the Western College of Veterinary Medicine.
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He was part of a large group of university and government scientists who worked with an industry committee to co-ordinate the national study. Manitoba and Quebec did not participate because they had done similar studies in the past and Newfoundland did not have enough beef cattle.
The study got off to a rocky start when it was first proposed five years ago. The drought of 2002 and onset of BSE in 2003 delayed the work and producers who worried about their future were reluctant to participate.
Blood samples were eventually collected from 4,778 cows and about 1,500 weaned calves. Herds ranged in size from 10 to 540 cows.
“We didn’t get quite as many herds as we had wanted to get but it was still no mean feat to get that many herds recruited and that many cows bled across Canada,” Campbell said.
Blood samples were tested for disease antibodies, the presence of which may have meant only that animals had been exposed to a disease at some point and not necessarily that they had been infected.
The final results showed neospora was the most common disease. It is associated with a parasite and causes abortions in beef and dairy cattle.
The scientists found 6.2 percent of all cows tested positive and 65 percent of herds had at least one positive cow. The disease can be spread in the feces of dogs, coyotes and foxes in feed or water. Mothers can infect their offspring.
A vaccine is available but good management and cleanliness on the farm goes a long way toward eliminating disease.
Producers who said they had noticed more than the normal numbers of coyotes or foxes near their farms tended to have higher levels of neospora. A fox, dog or coyote that eats the aborted fetus from an infected cow can also become infected and then pass on the disease by leaving its feces in hay.
Farms also had a higher risk of neospora if they confined cattle during calving or used standing water for drinking.
Bovine viral diarrhea showed up in 20 percent of calves. BVD is a complicated disease and blood tests looked for the amount of medicine or antibodies found in blood, measuring them in units called titers.
“We know that is a very common disease in Canada and many cattle are exposed to it,” Campbell said.
“The titers become more difficult to interpret though because some of the calves were vaccinated.”
However, nearly half the calves tested showed no titers so they were either not vaccinated or exposed to BVD.
Johne’s disease is a chronic wasting condition of cattle caused by infection with the bacterium mycobacterium paratuberculosis. The good news was that less than one percent of cows and 4.5 percent of herds tested positive for the disease, which is a much lower incidence than what is seen in dairy herds.
Only 1.2 percent of cows tested positive for the viral infection enzootic bovine leukosis and 11 percent of the herds had one cow that tested positive.
Leukosis is spread primarily through the blood when needles or surgical instruments for dehorning and castration are not cleaned between animals. Biting insects can also spread the disease.
Overall results are still being analyzed and will be published soon. Useful as a baseline study, the survey shows the Canadian beef herd is healthy with low levels of infectious disease.
The information can be presented to trading partners concerned about disease management, and can also help improve disease prevention on the farm by encouraging sanitary practices.
Campbell said many problems can be controlled or stopped with basic biosecurity principles. The scientists want to publish a paper on cow-calf biosecurity practices, based on results from this study, to prevent disease.
