Sheep Breeding Improvements Arise from ARS-University
By Jan Suszkiw
October 19, 2009
Artificial insemination (AI)
techniques that work well with cattle and swine can be difficult or costly to
perform in sheep, but helps on the way, thanks to
Agricultural Research Service (ARS)
studies in Fort Collins, Colo.
There, at the agencys
Center for Genetic Resources Preservation, animal physiologist
Purdy and colleagues are working to improve both the handling of sheep
semen and the artificial insemination of ewes, whose cervix is difficult to
traverse with traditional AI tools. Purdy is collaborating with ARS animal
Blackburn and University of Wyoming
scientists Bob Stobart and Brent Larson on the effort.
The teams studies showed that sheep semen can be collected and
shippedin cooled liquid formovernight before freezing without
harming its in-vitro quality. They further determined the semen could be
cryopreservedor frozenafter shipping without reducing its success
in surgical AI.
Their studies also compared semen that had been cryopreserved after
collection to semen that had been frozen after 48 hours (the time required to
ship samples across the country). No differences were observed in semen
quality, fertilization ability, or number of lambs born to ewes surgically
inseminated with the samples. Potentially, this could open the door to sheep
producers use of samples from around the world, expanding and improving
their breeding options, according to Purdy.
On another front, his team adapted a swine insemination method for use in
ewes. It involved using a spiral insemination catheter to traverse the
ewes cervix and deposit thawed semen directly into the uterus. The method
takes about two minutes per sheep and costs $1.29. Though faster, less costly
and easier than laparoscopic surgical insemination, the new method so far has
had a lower success rate: about 55 percent using fresh semen and 10 percent
using frozen semen.
The researchers are investigating how to hone the technique and improve its
success rate by improving the timing of estrus and insemination.
more about this research in the October 2009 issue of Agricultural
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.