Technical information - selection

Polled gene marker offers significant benefits

BRAHMAN NEWS SEPTEMBER 2010 Issue #168



A new DNA test to identify polled Bos Indicus cattle was launched at the Royal Brisbane Show in August.

The new gene marker identifies whether cattle are “true polled”, as a visibly polled animal may still carry a recessive gene for the horned trait and throw a proportion of horned offspring. This mixed heterozygous genotype is also associated with scurs, which are incomplete horns.

While the polled DNA trait has been reasonably well understood in European breeds, the Australian beef industry needed a test developed for Bos Indicus breeds used in Australian production systems.

The breakthrough is the result of studies by Beef CRC, which undertook the research with CSIRO and Meat & Livestock Australia, in collaboration with the Animal Genetics and Breeding Unit (AGBU), and could help improve industry productivity and animal welfare by breeding out horns.

In the seven breeds used for field testing – Brahman, Santa Gertrudis, Droughtmaster, Limousin, Hereford, Brangus and Belmont Red – the test’s accuracy of a true polled animal having a polled phenotype was approximately 90 percent.

Wayne Hall, Manager Northern Production Research, Meat & Livestock Australia, said there were welfare and productivity gains to be made from introducing more polled cattle into the herd.

“Because cattle in the north are often run in extensive production systems, you may not see a calf until it is 6-12 months old, and dehorning older calves involves greater welfare considerations,” he said.

“What a gene marker does is provide an additional tool to speed up that process, and provide a higher level of confidence. But we need to know how well the test works in wider populations first.”

ABBA general manager John Croaker, who spoke alongside MLA chairman Don Heatley at the launch of the test in Brisbane, said the incidence of polled cattle in the Brahman breed had increased significantly in the past five years.

”Last year nearly 10 percent of our grey calves and nearly 30 percent of our red calves were polled or scurred,” Mr Croaker said.

“The ability to separate the homozygous polls will improve the accuracy of selection and increase the frequency of the polled gene.”

Dr Heather Burrow, CEO of the Beef CRC, said industry’s experience with DNA markers was that they could sometimes “over-promise and under-deliver”.

“We needed a test that is validated in Australian breeds, so producers can be confident in using it to make selection decisions for polledness.”

The new test will first be released to industry in a trial phase, following initial successful outcomes of research trials conducted across Australia. Dr Burrow said if the test results were replicated in wider cattle populations, the gene marker would be very useful for industry. However, she said the test was not perfect and producers were strongly encouraged to report anomalies to the research team.

During its initial validation phase, the test will be offered at minimal cost through the ABBA. The test is conducted by The University of Queensland’s Animal Genetics Laboratory and producers need to supply 30-40 hair follicles and details of the phenotype of the animal being tested (i.e. horned, polled, scurred or unknown).

By participating in the project, producers will be increasing their information on the genotypes of their animals, as well as helping to road test a technology that may assist in breeding out horns.

For more information contact the ABBA on 07 4927 7799.