Scrapie resistance and production traits in Rambouillet rams: Ram performance test 2002–2006

Sheep possessing alleles for the prion protein with glutamine (Q) or histidine, both reported as Q, at codon 171 are highly susceptible to scrapie. Incidence of scrapie infection is rare when animals possess at least one allele for arginine (R) at codon 171. The current USDA APHIS scrapie eradication program utilizes genotyping for alleles that confer resistance to scrapie. Although it has not been a criterion of registration, genotyping has been utilized in the University of Wyoming Ram Performance test since 2002. Performance test records from 2002 to 2006 (n = 518) were analyzed to determine if any production loss or benefit was associated with scrapie resistance in rams. Performance of rams with scrapie resistant genotypes was equal to or better than scrapie susceptible rams. Based on test performance as an acceptable indicator of sire superiority, selection for rams with scrapie resistant genotypes should not negatively impact flock performance.