It was a scourge that hadn't gripped the U.K. for more than 30 years. Then in 2001, an outbreak of foot-and-mouth disease began killing the country's Herdwick sheep in droves. The disease devastated the ancient breed, well adapted to the cold, wet hills of England, over the course of a tumultuous year that cost the U.K. an estimated $16 billion in total damages. In 2010, the same feared ailment hit Japan’s coveted herd of Wagyu beef cows. Just a handful of important breeding bulls survived the epidemic.
Concern that similar plagues will strike again has prompted organizations and governments around the world to take action to protect the world’s livestock assets. Their latest weapon: "meat banks" stocked with frozen semen and ovaries from the key animals that provide us with meat, milk and eggs. The goal is to maintain a broad genetic base within some of the most commercially important species, as well as to preserve potentially valuable genetic traits found only in rare heritage breeds.
“Production and fertility issues could arise if the diversity of a breed’s genetics isn’t maintained,” says Harvey Blackburn of the National Animal Germplasm Program, run by the U.S. Department of Agriculture. “You might also have a catastrophic event like the outbreak of foot-and-mouth disease in England, which actually threatened a number of breeds. Using our collection, you could actually reconstitute those populations.”
Bolstering food security with genetic banks is not a new concept. Perhaps the most well known facility is in Norway, where a vault built into the base of a mountain holds frozen seeds from virtually every known food-producing plant species. The Svalbard Global Seed Vault is meant to serve as a backup system that could help repopulate fields and orchards with food staples should a disastrous pest or weather event eliminate any crops from production.
But the livestock industry is trying to play catch-up. Preserving animal DNA is much trickier than maintaining a library of plants, according to Blackburn. Seeds are very hardy and can be dried and preserved almost indefinitely. Even cloning is an easy task in the horticultural world. Duplicating a favorite fruit tree may be as simple as planting snipped-off branch tips in the ground, where they will grow into a new plant. By this method, a certain variety can be propagated indefinitely, its traits perfectly preserved and the cloned organism essentially made immortal.
By contrast, animal DNA can only be preserved through much more cumbersome means. The simplest way to do it may be via live animals—say, a flock of strategically bred sheep. However, this requires coaxing the animals into mating and then perpetually helping to birth and rear new specimens. Even then, the offspring are not the same as the parents but are genetic reconfigurations. Through many generations of sexual reproduction, genetic drift can occur, which changes the species and may affect its desirable traits.
The alternative method of preservation is to freeze animal DNA, mainly via semen. Samples must be kept in containers of liquid nitrogen as a security measure against temporary power outages. Once thawed, the lifespan of cattle sperm may be 12 hours or more, while catfish sperm dies if it doesn’t find an egg in just several minutes. But as long as things stay chilly—the USDA keeps its collection at about -300° Fahrenheit—freezing causes no damage to the sperm, Blackburn says. There is reason to believe that frozen reproductive cells can survive without ill effect for as long as 1,000 years.
“We have done experiments with cattle semen frozen in the 1960s and compared it to early 2000s and found no difference in pregnancy rates,” Blackburn says. Currently, the USDA facility in Colorado has amassed more than 800,000 frozen samples from about 26,000 animals. The collection, made up of common livestock species as well as fish and shellfish, includes 36 species represented by 155 breeds. Though relatively small in the global spectrum of animal species, the inventory is the world’s largest of its sort, according to Blackburn.
To stock its freezer, the program calls on farmers who own exemplary bulls, boars, rams and roosters to provide samples of animal semen, which must be chilled and overnighted to the facility. First-time sperm donors are selected after detailed reviews of their pedigree records, to ensure that the animals are not closely related to any which have already contributed to the collection. In turn, farmers wishing to introduce new genes into their private herds may request semen samples from the facility. Blackburn says semen orders come in daily, and just as frequently, the facility’s staff mails out straws filled with the reproductive fluid.
The USDA’s livestock germplasm bank also keeps frozen chicken ovaries and testes, which Blackburn says may be transplanted into breeding females and males, as well as frozen blood samples. These are used mostly for DNA analysis purposes. Blackburn adds that cloning research is not a priority of the USDA.
But while many animal breeds are safely secured in the world’s cryogenic livestock banks, hundreds of heritage breeds are still at risk of extinction. Currently, one rare livestock breed vanishes every month, on average. “In most cases, the original wild ancestors of these animals are also extinct, so it’s not possible to bring them back once they’re gone,” says Ryan Walker, communications director with The Livestock Conservancy.
Based in Pittsboro, North Carolina, the non-profit group has been working since the late 1970s to identify rare or threatened breeds of cows, horses, sheep, goats, pigs and poultry and coordinate efforts to keep the animals in existence. The organization has helped save several of these heritage breeds but names dozens as still critically endangered. In most cases, these breeds have simply fallen out of fashion as mainstream agriculture replaced them with the more lucrative breeds that have come to dominate the livestock industry.
While heritage breeds may lack the qualities that make fast-growing and fertile commercial breeds so industrially important, some bear genetic traits that could be bred into mainstream animals to stave off inbreeding risks or introduce disease resistance or hardiness against the elements. The critically endangered Texas longhorn cow, for example, is extremely tolerant to arid conditions. It is attracting interest from cattle farmers in the U.S. West wishing to boost the hardiness of their animals in the face of long-term drought forecasts, according to Jeannette Beranger, research and technical programs manager with The Livestock Conservancy.
“[Texas longhorns] can eat sparse vegetation that other cattle would starve to death on,” Beranger says. Resistance to deadly parasites has already been bred into the U.S. goat population from Spanish breeds, she adds. And farmers now have their eyes on the critically endangered Gulf Coast native sheep, which has shown remarkable resistance against hoof rot and deadly parasites that have plagued the Australian sheep industry. Then there is the Egyptian Fayoumi chicken, which is totally immune to Marek’s disease, a tumor-causing virus.
“That,” she says, “is just one more example of what these animals have to offer modern agriculture, so we need to keep them alive.”
Editor's Note, 6/2: The photo at the top of this article has been updated to show purebred Texas longhorn cattle.