Watching four one-month-old baby bison graze and run through a field, you’d have no idea that they’re a reproductive breakthrough.
University of Saskatchewan (U of S) researchers say they’re the first in the world to produce three wood bison calves using in vitro fertilization (IVF) and one using a frozen embryo.
“That’s an amazing feat and it has taken a long time to get to this point, but we’re really excited. We have four healthy wood bison calves bouncing around in the pasture,” said Dr. Gregg Adams, a U of S veterinary scientist.
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A research team has been working since 2006 to learn about bison reproductive cycles, develop advanced reproductive technologies like artificial insemination, superovulation, IVF and cryopreservation.
Wood bison are indigenous to Canada, but only 5,000 to 7,000 bison remain in the wild—less than five per cent of their original numbers. Loss of habitat and isolated herds led to the loss of genetic diversity.
The species is also threatened by diseases like tuberculosis and brucellosis, which were introduced by exposure to cattle.
“Thirty to sixty per cent of the wild bison in the Wood Buffalo National Park, which is the biggest reservoir, are infected with brucellosis and tuberculosis. That’s hampered their population growth and it has also isolated them,” Adams said.
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A culmination of almost a decade of research has led the team to developing techniques to stop the spread of disease and hopefully repopulate the species with genetically diversified calves.
“We can physically wash the embryos and wash the semen free of these diseases; make the babies in vitro and then transfer them into healthy surrogate moms,” Adams explained.
“If we can take an appropriate sampling of genetics from different isolated herds in Wood Buffalo National Park then we can redistribute the otherwise narrowing gene pool.”
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Researchers have also developed bison-specific cryopreservation techniques for egg, semen and embryos.
“Developing cryopreservation techniques for bison semen has proven to be a real challenge and we’ve come a long way with that,” Adams said.
Dr. Muhammad Anzar is a cryobiologist working to produce and preserve disease-free semen, eggs and embryos.
Fridge, a calf aptly named because it was produced from an embryo frozen in 2012, was a world first. Anzar said having the ability to freeze genetic material gives veterinary scientists a better opportunity to diversify the species.
“We can use these frozen eggs, embryos and semen for shipments around the globe. This is the beauty of the cryo-preservation technology,” Anzar explained.
“Normally you don’t have the recipient cow waiting for you so you have to preserve the embryo and then any moment that is perfect for you, you can transfer these embryos if they are frozen,” said U of S veterinary PhD candidate Miriam Cervantes.
Cervantes works to gather the eggs and semen, fertilize the eggs, and transfer the embryo into the surrogate mother.
She named the four calves Moon, Storm, Hope and Fridge.
The advances in bison reproduction are also important for the livestock industry. Many bison producers like to cross prairie and wood bison because it creates larger and genetically stronger animals.
Now that the team has achieved their goal, they’re working to hone their techniques for better efficiency.