Genetic options to replace dehorning of beef cattle in Australia

Summary

Breeding polled cattle is a long-term solution to problems commonly associated with horned cattle. The current practice of dehorning is widely known to be like ‘treating the symptoms’, but ‘not eradicating the problem itself’. The present study reviewed the current state of knowledge on the genetic basis of polled inheritance in cattle. The polled / horned condition is controlled by a complex mode of inheritance through polled, scurs and African horn genes segregating independently, but interacting with each other to produce polled, scurred and horned animals. Molecular genetic studies have mapped the polled gene to a specific region on bovine chromosome 1, but the actual gene is still to be located. Scurs and African horn genes have not been studied thoroughly at a molecular level.

With the current advances in molecular genetics and statistical methods, new research programmes should be undertaken to develop DNA tests for identifying homozygous/heterozygous animals for polled, scurs and African horn genes to assist in faster introgression of the polled condition into beef cattle populations. Results from a simple simulation program in various scenarios of low and high frequencies of polled gene and African horn gene have demonstrated that knowledge of DNA tests for both polled and African horn genes can significantly hasten the process of increasing the proportion of polled animals. The proportions of horned and polled cattle in various southern and northern Australian breeds are estimated based on the breed association records. Industry perceptions on the issue of breeding polled cattle and existing scientific evidence to counter such perceptions are presented. Various research and extension strategies to be undertaken for achieving the goal of replacing dehorning through genetic options are outlined.