If there were ever a need to totally regenerate the Navajo-Churro breed from the ARS collection, a backcrossing strategy could be used. In such a situation, Churro semen would be used to inseminate a ewe from a different sheep breed. The resulting offspring would be 50 percent Churro. The process would be repeated using a female offspring, making the next generation 75 percent Churro. They keep doing this until the sheep are 93 percent Churro.
The collection could also be used by breeders or researchers to introduce genetic variation into existing Churro populations.
At one time, there were 2 million of these sheep. In 1977, when conservation efforts started, there were fewer than 500. Now the estimates are around 1,500.—By David Elstein, Agricultural Research Service Information Staff.
This research is part of Food Animal Production, an ARS National Program (#101) described on the World Wide Web at www.nps.ars.usda.gov.
Harvey D. Blackburn and Phil Purdy are with the USDA-ARS National Center for Genetic Resources Preservation, 1111 South Mason St., Fort Collins, CO 80521-4500; phone (970) 495-3268 [Blackburn], (970) 495-3258 [Purdy], fax (970) 221-1427.
"Making Sure Sacred Sheep Don't Become Extinct" was published in the April 2005 issue of Agricultural Research magazine.