The polled locus maps to BTA1 in a Bos indicus x Bos taurus cross

Two hundred and nine reciprocal backcross and F2 progeny produced by embryo transfer from Angus (Bos taurus) and Brahman (Bos indicus) parents and their 60 parents and grandparents were utilized to localize the locus (POLL) responsible for the polled phenotype in a genetic map of bovine chromosome 1. Progeny were scored for polled, scurred, and horned phenotypes at 1 year of age and again following skull disection at slaughter at 20 months of age. Phenotype frequencies were independent of gender. One hundred and forty-two informative meioses for POLL and 13 microsatellite loci with an average of 267 informative meioses per locus contributed to a genetic map spanning 124.6 cM with an average interval of 9.6 cM. POLL mapped proximal to the centromere and 4.9 cM from TGLA49 supporting a previous study that employed two anonymous microsatellites. Difficulties in discriminating between scurred and horned phenotypes indicate that bracketing markers will be essential for refining the model for inheritance of the horned, scurred, and polled phenotypes and for effective marker assisted selection (MAS) for polled.