Heterozygosity of the Celtic polled locus in Canadian scurred beef cattle

Abstract

Polled cattle are preferable to horned or scurred animals because they are safer for handling and cause less bruising. Although DNA testing can determine horned/polled genotype, scurs may appear in polled animals. The inheritance of scurs is complex because it is a sex-influenced trait that interacts with the polled locus. We demonstrate that in 685 purebred and crossbred Canadian beef cattle, all 153 scurred animals were heterozygous polled at the Celtic variant. In addition, male obligate carriers of scurs were smooth polled when homozygous for the polled mutation. Scurred and non-scurred males were sequenced for five genes (CTDNEP1, SHBG, SOX15, FGF11, and DHRS7C) within the scur candidate region on BTA19 that are functionally related to bone development and hormone regulation. Multipoint linkage analysis was conducted using 18 microsatellite markers and two informative variants (DHRS7C g.29594018G>C and CTDNEP1 c.462G>A) in the scurred families and further supported mapping on BTA19 between BMS2142 (logarithm of the odds (LOD) = 5.42) and IDVGA46 (LOD = 3.47). These data indicate epistatic interactions between the scurred and polled loci and emphasise the necessity for a scurred DNA test to assist purebred beef producers in eradicating the scur trait.