Investigating Scur Candidate Genes in Bos taurus cattle

Abstract

Scurs are loose horns that are inherited in a sex-influenced manner and appear in cattle that are heterozygous (Pp) for the polled mutation. Beef producers find them undesirable, but they are difficult to eradicate because of a complex inheritance. The aims of this study were: 1) to confirm the polled/horned genotype in scurred families from a Canadian beef research herd (CBRH), scurred cattle families from producers, and feedlot steers using the Celtic poll test (PC) and Friesen poll test (PF), and 2) to identify new candidate genes near microsatellite BMS2142 on BTA19. Through PCR amplification, the PC genotype was confirmed in the phenotyped CBRH, Simmental and Blonde D’Aquitaine (BA) scurred families, and in 625 feedlot steers. One hundred and forty nine scurred animals (out of 692) had one PC allele. PCR amplification revealed that the PF allele was present in four polled steers that were horned using the PC test. Five scur candidate genes (CTDNEP1, FGF11, SOX15, SHBG, and DHRS7C) were chosen based on position and function on BTA19. To identify SNPs segregating with scurs, 16 animals were chosen from the PC genotyped feedlot steers, 8 Pp scurred steers and 8 Pp polled steers. Two SNP’s found in CTDNEP1 and DHRS7C were examined in the CBRH and BA with PCR-RFLP using BseRI and AciI, respectively, but did not segregate with scurs. Multipoint analysis calculated by CRI-MAP 2.5.4, determined that there was significant linkage of the scur locus to two microsatellites on BTA19 (BMS2142 LOD=5.42; IDVGA42 LOD=3.47). In conclusion, this study’s fine mapping of the scur locus has increased the LOD scores of surrounding loci and was linked to two microsatellites on BTA19. Also, to identify scurs the animals should be carefully phenotyped and genotyped for PC, using the PF for inconsistent results in beef breeds.