High Country News: Postcard from a livestock sperm bank
March 7, 2014
On a dark, frigid December morning, Oogie McGuire stares out her window and down the gravel driveway, willing a truck to appear.
"We're racing against the clock," she says, frowning. It began ticking 72 hours ago when Oogie and her husband, Ken, who raise black Welsh mountain sheep outside Paonia, Colo., removed a sort of hormone-soaked sheep tampon from each of their ewes to induce simultaneous ovulation. Starting … now.
Fortunately, animal physiologist Phil Purdy's pickup soon arrives, and the team rushes the sheep through a series of gates. The McGuires strong-arm a carefully selected ram toward a ewe in heat. Purdy tricks him into ejaculating in an artificial vagina — without even resorting to the vial of sheep urine in his pocket, which "makes the boys go crazy" — and carries it to a makeshift lab in the garage, where technician Scott Spiller divides the semen into straws. Those not used to inseminate the McGuires' flock will travel some 300 miles across the Rockies and be frozen in liquid nitrogen alongside others collected by Purdy and Spiller, who visit farms and ranches across the country in search of eggs, semen and embryos from rare breeds. Once, in Connecticut, Spiller had to explain to a bewildered state trooper why he was transporting a load of rooster semen in his rental car.
The samples are all destined for the U.S. Department of Agriculture's National Center for Genetic Resources Preservation in Fort Collins, Colo. Variously described as the "sperm bank of the apocalypse" and the "Fort Knox" of genetic material, the building resembles any other on the Colorado State University campus. But behind its beige walls is a heavily fortified vault that can withstand floods, fires and tornadoes.
"Worst-case scenario," says Harvey Blackburn, director of the Animal Germplasm Program at the center: "A major disease outbreak in this country. We have" — he enunciates each word — "the ability to restore a population."
Like "Jurassic Park"? Blackburn is wary of such comparisons. In recent years, biologists have unlocked the secrets of "de-extinction," bringing species like Australia's gastric brooding frog (which gives birth by puking up its young) briefly back to life by implanting its DNA into the eggs of a similar species. The breakthroughs have captivated public interest — some enthusiasts even want a Siberian wildlife reserve for resurrected woolly mammoths. But though Blackburn talks about "reconstituting" a species as if cooking up dehydrated soup on a backpacking trip, he's not interested in stockpiling the genes of endangered wild animals. His goal is more utilitarian: preserving the DNA of animals that humans need for food or fiber.
The project began with seed saving in the 1950s, around the same time that American farmers were abandoning heirloom strains for more commercially viable varieties. As agricultural diversity declined, disease became more of a threat, and the science behind genetic preservation advanced. In 1999, the seed bank expanded to include animal germplasm; today, it's the most secure and comprehensive repository in the world. Its scope is too big for any zoo to take on, or for private enterprise to maintain in perpetuity. "It's the federal government's role to protect genetic resources," Blackburn explains. "They underpin agriculture and food security."
Inside the vault, curiosities such as oyster embryos, bison sperm and sterilized screwworms (used to kill fertile screwworms, which can devastate livestock) are suspended in vats of liquid nitrogen, along with 30,000 straws of salmon milt collected by the Nez Perce in Idaho. Altogether, there are 800,000 samples. If longhorn cattle ever get wiped out, for example, Blackburn's team could thaw their DNA and insert it into the eggs of another kind of cattle. Or if the genetic diversity of a rare breed gets too low, the repository could reinvigorate it.
Most samples are donated by farms and agribusinesses, then freely shared with other farms, universities and germplasm banks. The McGuires' role is especially vital; their obsessive recordkeeping aids Purdy's research. Because sheep semen doesn't freeze as well as that of other species — and because the U.S. bans most sheep importation — all the black Welsh sheep in the U.S. are descended from the same 11 lambs. If Purdy can figure out what factors are most important in successful freezing and insemination, breeders could eventually swap DNA across oceans, increasing their flocks' diversity without expensive surgery.
Who'd ever guess sheep farming could be so complex? "There's way more variables than you can possibly control," Oogie says, showing me the "LambTracker" data-collection software she designed in her scant spare time. She shrugs. "Sheep happens."
This article originally appeared in the Feb. 17, 2014, issue of High Country News (hcn.org).
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