October 16, 2006
Livestock Sperm Bank Preserves Species
NEWPORT, R.I. -- Just one of the Dutch Belted Cattle lazing in a corral overlooking the city's rolling hills costs $4,000 - a bargain considering its DNA is priceless.
Called Oreo cookie cows because of their three distinct stripes, Dutch Belteds were brought to the United States from Holland in 1840 by P.T. Barnum for use in his circus. Fewer than 1,000 are left worldwide.Concerned the animals could become extinct, the SVF Foundation is collecting germplasm - sperm, fertilized embryos, blood and tissue - from its cattle to try to preserve the breed. Dutch Belteds are one of 18 endangered breeds of cattle, sheep and goats the foundation hopes to save.
"In a way, we're producing the Library of Congress from the genetic standpoint of animals in the United States," said Dr. George Saperstein, a Tufts University veterinarian and the foundation's chief scientist.
While modern breeds produce better meat, milk and wool, many older, endangered breeds are more resistant to heat and illness - traits that make them worth preserving. If disease devastated a sheep population, farmers might want to revive the parasite-resistant Gulf Coast Sheep or crossbreed it with their animals to produce hardier offspring.
"Germplasm is like the best insurance policy in the world in case something happens to a large population," said Don Schrider, communication director for the American Livestock Breeds Conservancy.
The SVF Foundation is one of two significant germplasm repositories in the United States. The National Animal Germplasm Program run by the U.S. Department of Agriculture has a far larger collection, but SVF's stands out because of its emphasis on endangered breeds.
Campbell's Soup heiress Dorrance Hamilton established the foundation in 1998 on a property in Newport that includes the Swiss Village, a restored turn-of-the-century dairy farm, and part of Hammersmith Farm, Jacqueline Kennedy Onassis' childhood home.
Concerns about disease - spread from animal to animal, person to animal or test-tube to test-tube - prompt strict security. The farm is closed to the public; visitors must walk through a sterilizing solution before stepping onto the grounds.
To preserve a single breed, the foundation will collect 200 embryos, 3,000 vials of semen and tissue samples containing DNA that may be useful down the road. The process costs hundreds of thousands of dollars, director Peter Borden said.
The investment is well worth it if it protects the nation's agricultural industry, Saperstein said, noting that a heat wave in California killed tens of thousands of Holsteins this summer.
"If the farmers had Jersey cows, they'd all still be alive because the Jersey cow is much more tolerant of heat," he said.
Heritage breeds - those found in the United States in the 1700s and 1800s - tend to be hardier, with greater immunity, better mothering skills and an ability to forage often lacking in modern commercial breeds. Some also serve multiple purposes, such as the Milking Devon cow, which provides milk and beef and can be used for farm work.
"It's not science fiction to say we could pluck these genes from rare breeds and put them into modern breeds in the near future," Saperstein said.
The science of preservation combines common agricultural practices with veterinary medicine and techniques used in human infertility treatment.
Females receive hormone injections to increase their production of eggs. Workers artificially inseminate cows because bulls are not kept on the property. The foundation's sheeps and goats mate naturally.
About a week later, veterinarians collect the embryos. They put goats and sheep under anesthesia and flush the fertilized eggs from their wombs. The procedure can be done to cows while they are awake.
Healthy embryos are placed in thin vials called straws and stored in liquid nitrogen. Seventeen thousand straws filled with embryos and bits of semen - the bulk of the foundation's collection - fit in a tank the size of a water heater. Alarms sound if the tank's temperature is off by even one degree, and the foundation is armed with backup generators in case of a power outage.
When the foundation finishes collecting material from one breed, it thaws a few embryos and implants them in a surrogate mother to test the process's viability. Its first embryo transfer produced Chip, a Tennessee Myotonic goat born to a Nubian doe. Its second produced Howie, a Gulf Coast Sheep born to a Santa Cruz ewe.
The embryos could be used to resurrect an extinct breed within one generation. Saperstein said that's important because worldwide farmers are losing one to two breeds per week.
On the Net:
SVF Foundation: http://www.svffoundation.org