New research into Johne's disease is aiding in the understanding of a threat to the dairy industry. A recent three-year study into how age and bacterial load affect all dairy cows led by Jeroen De Buck found that all cows are susceptible to infection. Previously, it was thought that cattle six months of age and younger were most susceptible to the cause of the disease.
New research into Johne's disease is aiding in the understanding of a threat to the dairy industry.
A recent three-year study into how age and bacterial load affect all dairy cows led by Jeroen De Buck found that all cows are susceptible to infection. Previously, it was thought that cattle six months of age and younger were most susceptible to the cause of the disease.
Through a study of various ages of cattle from 2010 to 2013, it was found that all cattle studied, regardless of age, were susceptible to the disease. The study found that exposure to the bacteria Mycobacterium avium subspecies paratuberculosis (MAP) was more of a factor in cattle infection than age.
"We found in the study that calves, when they are infected, shed (bacteria) earlier on – after three months – so there's a potential for the calves to infect their pen mates when they are group housed. Before, it wasn't (understood) as much that those calves would already start shedding, because typically it takes up to two years or so before they would start shedding these bacteria in their feces," he said.
De Buck said his University of Calgary research team previously found that one or two per cent of young calves are already infected with MAP and shedding the bacteria in their feces.
The team has been actively researching Johne's disease for the past eight years, and has several students working for the research team.
"What we are doing now is to see the level at which the calves shed at … are actually enough to infect other calves," he said.
The importance of the research is to add to knowledge that was previously known about Johne's disease.
"There's no age that we know at least not before one year old that calves are susceptible. Before, people would say that after six months (of age) we don't have to protect the calves … we argue that yes, you need to protect them. It's important for dairy farmers to try and keep the infection pressure on a farm as low as possible," he said.
De Buck said the research team wants to follow up on this study by experimentally infecting calves with MAP and then placing them in the same barns as non-infected calves to see if the infection spreads among the herd.
Another strand of research involves using the infection model the team has discovered to develop a vaccine against Johne's disease.
"We just started on developing a disease vaccine and it's early stages … but we know we have a good model that we can test and see whether this vaccine that we're developing can protect (the cattle)," De Buck said, noting that the team also evaluated strains of the disease that are prevalent in different regions of Canada to make sure that any vaccine that is eventually developed will be effective against the dominant strains of the disease.
"If we want to make a vaccine we argue that we better make the right one that eventually would be protective against … at least the predominant strains that are out there."
De Buck said he is confident that his team will also be able to develop a better diagnostic method than is currently available to detect Johne's disease and thereby prevent some of the effects the disease has on the dairy industry.
"We're optimistic but cautiously, because it's not straightforward," he said.
"It's important for dairy farmers to try and keep the infection pressure on a farm as low as possible."Jeroen De Buck led study into Johne's disease
