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Information gathered on a sheep and its relatives
is helping ARS scientists learn just how much a trait is affected by genes or
by nongenetic factors. Click the image for more information about
it.
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Genetic Underpinnings of Sheep Traits May Yield Clues to
Greater Productivity
By Jan Suszkiw
August 15, 2008 Keeping America's sheep healthy and
productive while expanding the market for wool and lamb is the goal of
Agricultural Research Service (ARS)
scientists who are matching the animals' physical traits to the genes that
underpin their expression.
The scientists are pursuing this research mainly at three ARS locations: the
Animal
Diseases Research Unit (ADRU) in Pullman, Wash.; the
U.S.
Sheep Experiment Station in Dubois, Idaho; and the
Roman
L. Hruska U.S. Meat Animal Research Center in Clay Center, Neb.
At Dubois, the team led by
Gregory
Lewis is investigating reproductive efficiency, mineral retention and other
traits.
Michelle
Mousel, an ARS geneticist at Dubois, has also created a bank of frozen
tissue specimens from the station's on-site flock of 6,000 lambs, ewes and rams
in support of that work, as well as data analysis and genotyping efforts.
At Pullman, ARS scientists
Lynn
Herrmann-Hoesing,
Stephen
White and
Donald
Knowles, who leads ADRU, are using the tissue samples to study whether
ovine progressive pneumonia virus levels are affected by specific sheep immune
response genes. Their goal is a molecular test with which to measure the levels
of such infectious agents in sheep.
Scrapie, a degenerative neurological disease of sheep, is another concern.
At Clay Center, ARS microbiologist
Michael
Heaton and colleagues used DNA analysis and genotyping procedures to
identify sheep with 21 prion gene alleles (alternate forms of a gene) that
influence genetic resistance to scrapie. The advance has given rise to faster,
better and cheaper methods of detecting scrapie susceptibility in sheep and
eliminating their predisposition to the disease through selective breeding.
Parallel studies under way at Clay Center and Dubois focus on the so-called
myostatin mutation in Texel sheep. Through conventional breeding, researchers
eventually may be able to harness the mutation to increase the size of lamb
chops without adversely affecting tenderness.
Read
more about this and related research in the August 2008 issue of
Agricultural Research magazine.
ARS is a scientific research agency of the U.S. Department of Agriculture.
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