Summary
The objective of this project was to develop gene marker tests for the Polled, Scurs and African Horn genes. A microsatellite marker was found that is very closely associated with the polled locus in Brahman, Santa Gertrudis, Hereford, Droughtmaster and Limousin. In these breeds animals homozygous for the allele associated with polled almost never have horns or scurs, so no additional test for the scurs or African horn gene is required. In Tropical Composite cattle, those that are homozygous for the allele associated with polled are most likely to be polled, but also may be horned or scurred. This may be due to incomplete association, or due to another region of the chromosome such as the hypothesised African Horn gene. The marker test will facilitate the introgression of polledness in tropical beef cattle, such that the practice of dehorning can be phased out.
