Working to save Wood bison
Success hinges on finding ways to produce disease-free calves
By Colleen MacPherson
The small herd of Wood bison delivered recently to a special U of S facility south of Saskatoon, will be pivotal in a collaborative effort to save their threatened species.
Pockets of tuberculosis and brucellosis plague the Wood bison population that typically roams northern Canada and Alaska, explained Murray Woodbury, professor and Specialized Livestock Research Chair at the Western College of Veterinary Medicine (WCVM). Securing the animals’ survival will require the preservation of disease-free genetic lines, he said, and the WCVM bison will be used to help researchers understand how that process can be done successfully.
“The issue is how to get disease-free bison from a diseased herd,” he said, and techniques like in vitro fertilization, which have already been shown to work with bison sperm and eggs. “We can create a new little bison in a Petri dish but the gap in knowledge is knowing when to put the fertilized egg into a surrogate mother, and what to do to that surrogate to get a successful outcome.”
The answers lie in understanding female bison reproductive physiology so, for the first time ever, ultra-sound will be used on the Saskatoon herd to visualize, in real time, the animals’ ovaries. Those observations, made throughout the reproductive cycle, will be correlated with hormone changes and breeding behaviours, said Woodbury. The result will give researchers a clear picture of exactly when embryo implants have the best chance to succeed.
Based on the knowledge gleaned from the Saskatoon research herd, eggs and sperm can be harvested from diseased animals, cleaned, and implanted in disease-free Plains bison that will act as surrogate mothers. The result, said Woodbury, will be healthy genetic representative Wood bison calves.
Woodbury’s efforts to obtain bison for this reproduction study go back to 2004 when the University negotiated for animals from the Northwest Territories’ Hook Lake Wood Bison Recovery Project. Unfortunately, those bison tested positive for the diseases that were originally introduced into the wild population by humans, he said. In the 1930s, Plains bison were mixed with cattle carrying tuberculosis and brucellosis near Wainwright, Alberta. Wood bison picked up the diseases through exposure to those infected Plains bison.
The result is that today’s Wood bison herds experience death rates from disease that balance the birth rates, said Woodbury, making it almost impossible for the population to recover.
He pointed out that tuberculosis and brucellosis have been eradicated in the Plains bison that populate western Canada and as far south as Texas and Mexico. The 25 Wood bison at the WCVM’s wildlife research facility are also disease-free. They come from Parks Canada’s Elk Island National Park east of Edmonton and, like all Parks Canada bison, “have been tested six ways to Sunday. There’s a very rigorous strategy for disease surveillance in these animals to ensure the rest of Canada and its cattle herd is free of these diseases.”
The animals are the federal government’s contribution to the Wood Bison Reproductive Group that will carry out the research, a collaborative entity involving the park service, the WCVM, a scientist at the University of Calgary, a Calgary Zoo veterinarian and officials of the NWT government. It is important, said Woodbury, “to use the expertise that’s available across western Canada.”
The bison reproduction study is set out over roughly five years, he explained. Step one has already begun, which is “to see if we can actually handle these animals on a daily basis without killing them, or us.” The 22 females and three males are almost two years old “and they’re a bit wild so we have to get them accustomed to human presence. The first time they see a human, they run to the other side of the pen. By the 10th time, it’s ‘Oh, it’s you’.”
Once the animals are acclimated, the ultra-sound studies can begin. Eventually, the researchers will explore ways of manipulating the bison reproductive cycle as is done in cattle to increase the success of timed inseminations and embryo implants.
Woodbury is optimistic that with a better understanding of bison reproduction, the time will come when young, healthy Wood bison will carry their genetic lines back into the North.
“The biggest barrier to repopulating the northern wilderness with Wood bison is the presence of tuberculosis and brucellosis,” and the Wood Bison Reproductive Group may well be the species’ best chance for long-term survival.