August 15, 2003
Off-Lead Story -- Banking on the Future Of Livestock Production
A national germplasm repository in Colorado is helping to ensure the future of livestock production and sheep genetics.
By Tharran E. Gaines
Although Webster?s dictionary lists several definitions for the word ?bank,? the one that most often comes to mind is ?a place of safekeeping or storage for money or other valuables.?
Still, that?s a good way to describe a unique, USDA-operated bank based on the Colorado State University campus in Fort Collins, Colo. Officially known as the National Animal Germplasm Program, the assets stored within the Colorado facility may, indeed, be invaluable to livestock producers throughout the world. The goal of the program is to create a genetic repository that could help re-establish lost breeds in the event of disease, bioterrorism or years of inbreeding or abandonment by the industry.
According to Dr. Harvey Blackburn, program coordinator and an animal geneticist, the gene bank was established in 1999 by the USDA?s Agricultural Research Service (ARS) following an act of Congress in 1990 that authorized the conservation and maintenance of agricultural genetic resources.
As a result, the USDA/ARS created the National Center for Genetic Resources. In essence, it paired the National Animal Germplasm Program with the National Seed Viability and Storage Research Center, established on the CSU campus in 1957. The latter, often referred to as the ?seed bank? or ?seed storage lab,? is a collection of more than 340,000 seed varieties for the preservation of the nation?s most important agricultural crops.
Despite their short four years in existence -- which was delayed for nine years until funding was established -- the National Animal Germplasm Program has already amassed approximately 65,000 units of semen and 750 embryos from 42 breeds of cattle, sheep, hogs, goats and poultry. Of that total, the genenome bank has genetic resources that represent 13 different breeds of sheep and two breeds of goats.
?In total for the sheep, we also have semen from 224 different rams,? says Blackburn. ?However, what we?re trying to do is have at least 50 different unrelated animals of each breed represented in the collection. Consequently, if we?re trying to ensure the viability of the Suffolk breed, we?d want at least 50 different rams from that particular breed in the collection.?
Blackburn points to the slaughter of more than four million head of livestock in the United Kingdom in 2001 as an example of how quickly populations can become endangered. In that case, it was the outbreak of foot-and-mouth disease that led to such a close call within a nation?s borders. In fact, it?s estimated that nearly 40 percent of all Herdwick stocks -- a dark gray or brown breed unique to England -- were destroyed in just a few months.
?The germplasm bank is basically an insurance policy,? he says. ?If we were to ever lose most of a gene pool due to a disease, we would hopefully be able to re-establish the animal populations that have been lost.?
In some cases, there may also be some value in going back in history to retrieve genes that have been lost through crossbreeding or inbreeding. As an example, it is estimated that two bulls make up a third of the global gene pool within the Holstein dairy breed, while one bull makes up 23 percent of the gene pool within the Jersey breed. The result has been problems related to inbreeding within a number of cattle herds worldwide.
?Similarly, there?s a feeling that the Duroc hog breed has lost much of its eating quality, and a lot of people would like to go back to the pig of 10 or 15 years ago and use those genetics instead of the ones we have today,? says Blackburn. ?There are also a lot of breeds, like the Florida Cracker, or swamp cattle, that have been left behind by modern breeding programs and, as a result, are in danger of extinction.
?Consequently, our first priority is to get all the U.S. breeds backed up,? he adds. ?After that, we would be very interested in trying to capture genetic resources from populations outside America. One that sticks out in my mind for sheep is in central Asia, where it is believed sheep originated.?
In the meantime, however, the germplasm program has already collected semen and/or embryos from sheep varieties that vary from Suffolk, Rambouillet and Dorper to Gulf Coast native sheep, which are currently considered to be a rare breed. Although the material is provided at no cost to qualified participants, it is not limited to scientists or universities.
?One thing we don?t want to do is compete with anyone who has a business of selling germplasm,? Blackburn relates. ?In other words, if someone is trying to get semen from a popular bull or ram from us, when it is still available from an AI company, we?re not going to give it to them. We also require anyone who is requesting germplasm to fill out an application which must be reviewed and approved by a committee before anything is released.
?If, for example, an association or a group of producers were trying to develop a new line of sheep, we would consider releasing a sample for that sort of thing,? he continues. ?But we?re not going to give out a sample without adequate justification.?
When it comes to finding samples to add to the collection, Blackburn says he and his staff look to a number of sources. Although they have developed methods to take collections in the field and ship them back to Fort Collins, they also depend heavily on some of the AI companies to provide material.
?On the beef cattle side, we are lucky enough to have semen from some of the original Limousin and Simmental bulls that were imported into the U.S. back in the early 1970s,? he relates. ?Someone kept those in their tank all that time and decided this was a better place for it than in their inventory. Unfortunately, with sheep, we don?t have a very vibrant AI sector, so we don?t have the stud companies that we can go to for help. As a result, we?re often having to go out to individual farms and ranches to collect material.?
Once the samples are brought back to the facility, they are stored at minus 220 degrees Fahrenheit in liquid nitrogen contained in large, 5 1/2-foot diameter tanks. While the life expectancy of semen is not known, Blackburn says sheep semen has proven to be viable after 25 years or more in storage.
?There have also been studies with mouse embryos where they have been bombarded with about 1,000 years of radiation and still produced live mice,? he recalls. ?So we?re talking about long-term storage at any rate.?
Although the primary focus of the germplasm program to date has been livestock species, Blackburn would also like to eventually add genetic material from aquaculture species, which would include commercial fish species such as catfish, salmon, trout, shrimp and clams. In the meantime, he estimates the center is at about 10 percent of where it would like to be in the near future.
That certainly doesn?t take anything away from the program?s accomplishments, though. On the contrary, Blackburn says there have already been several spinoff benefits. One of those has been a protocol to cryopreserve ram semen using several different extenders and additives.
Blackburn has also been working with Virginia Tech and Virginia State University on a project to import hair sheep into the United States. While Blackburn?s interest is in adding samples to the repository, the universities are looking at commercializing the species.
It may still be several more years before Blackburn and the National Animal Germplasm Program meets all of its goals. Until then, however, you can be assured that the future of sheep genetics is in good hands and that the livestock industry can withstand any setbacks man or nature can dish out.