The Minnesota Zoo is hoping to improve the genetic diversity of the state's bison herd.
Using a new breeding method from Colorado State University, researchers transferred embryos from valuable Yellowstone National Park bison into four bison that are part of the Minnesota Bison Conservation Herd, the Minnesota Zoo said in a news release.
The hope is these bison will give birth to healthy calves this spring, and will go on to help expand the genetic diversity of bison in Minnesota.
What makes Yellowstone bison valuable?
There used to be 30-60 million bison roaming the United States and much of Minnesota, but during the late 19th century they were hunted to near extinction.
Efforts to restore bison have been successful, but in the process their genes have gotten mixed with domestic cattle because of inbreeding. This changes the bison's genetic makeup and could alter the appearance and adaptability of the species, the Minnesota Zoo reported.
It's estimated that fewer than 1 percent of the world's American plains bison are free of cattle genes, including bison living in Yellowstone and in the Minnesota Bison Conservation Herd.
Bison free of cattle genes are wanted to preserve the bison population in North America, and because Yellowstone bison genetics aren't well represented in Minnesota, their genes are "extremely desirable" for increasing the herd's genetic diversity, the zoo says.
So about this new research?
You can't just introduce a Yellowstone bison to a Minnesota bison, have them mate, and end up with genetically diverse babies.
In fact, the zoo says obtaining a sexually mature bull to breed naturally "has been impossible." That's because there's a transfer moratorium for Yellowstone bison due to the contagious disease many of them carry, which causes spontaneous abortions in pregnant females.
"The Yellowstone genetic is considered the Holy Grail of genetics because the animals cannot be removed from the park because of disease. It's hard to get them in a natural way," DNR Regional Resource Specialist Molly Tranel Nelson told KEYC.
So, researchers at Colorado State University came up with another way to increase the genetic diversity of bison herds. They used in-vitro fertilization to create an embryo made by bison in Yellowstone, treat the embryo to prevent the disease from being transmitted, and freeze them.
Those frozen embryos can then be implanted into other bison elsewhere.
That's what they did for the bison in Minnesota, and in the coming months veterinarians will do an ultrasound to confirm the animals became pregnant.
Dr. Jennifer Barfield, of Colorado State University, said she was "very pleased with how smoothly the embryo transfers went."
“While a new calf with valuable Yellowstone genetics would help augment the genetics of the Minnesota herd, it will also demonstrate that we can use reproductive technologies to move the Yellowstone genetics outside of the park without the threat of spreading the disease brucellosis, which has implications for bison conservation on a broader scale.”
Minnesota Bison Conservation Herd
The Minnesota Zoo and the Minnesota Department of Natural Resources have been working together since 2012 to preserve the American plains bison in Minnesota.
Bison are living at the Minnesota Zoo, and some that have tested free of cattle genes have been introduced to two Minnesota State Parks. There are currently about 90 living at Blue Mounds State Park, and 11 bison were released at Minneopa State Park last fall.
The zoo and DNR hope to increase the Minnesota Bison Conservation Herd to 500 animals.