THE influence of DNA-based selection tools for use within the northern beef industry has taken another giant leap forward following the launch of the world's first DNA test to identify polled Bos Indicus-influenced cattle.
The test's official launch took place on Thursday during the opening stages of the 2010 Royal Queensland Show, where a record 366-head led steer competition was under way.
The ability to apply selection pressure for polledness within Indicus cattle has major implications, both from a productivity and animal/human welfare perspective.
Following extensive res-earch conducted across Aust-ralia, the new test will initially be released in an industry validation phase.
Contributors to the project include the Beef CRC, CSIRO and MLA, in collaboration with the Animal Genetics and Breeding Unit.
Beef CRC chief executive Dr Heather Burrow said that, while the polled gene trait was reasonably well understood in British and European breeds, the Australian beef industry also needed a test for Indicus cattle used in many northern production systems.
"Industry's experience with DNA markers is that they can sometimes over-promise and under-deliver," she said. "We need a test that is validated in tropically adapted breeds, so producers can be confident in using it to make selection decisions for polledness."
Cattle bred for northern conditions are predominantly horned - a key cause of brui-sing, hide damage and injuries to man and beast, particularly in yards, feedlots and during transport. For this reason, de-horning is routinely practised.
The new DNA test identifies whether cattle are 'true polled', as an animal with a polled appearance may still carry a recessive gene for the horned trait and produce a proportion of horned offspring.
MLA northern production research manager Wayne Hall said welfare and productivity gains were to be made from introducing more polled cattle into the northern herd.
"Northern cattle are typically run in extensive production systems where calves may not be seen until they are six to 12 months of age. Dehorning older calves involves greater welfare considerations and is more labour intensive," he said.
A gene marker would provide breeders with an additional tool to speed up the process of getting more polled animals into their herds.
Veteran Charters Towers beef producer Tom Mann has been a strong advocate for research into polledness selection for the past 20 years.
"With polled cattle I can get an extra two animals on every deck, and that equates to a considerable saving in freight cost, as well as less bruising," he said. "It's also much safer for people handling cattle."
Mr Mann said he welcomed a test where producers could determine straight away whether or not a beast was going to produce a calf with horns.
"That will allow us to make selections much earlier, when we have bigger mobs of cattle from which to choose. Previously, selecting polled heifers or bulls has meant selecting at a later age, from a much smaller pool of cattle."
The project's next step is to determine how well the test works in bigger populations, to ensure producers can confidently utilise the tool in North Australian conditions.
Trials show the DNA marker is closely associated with the polled characteristic, although only small numbers of animals have been tested so far.
In the seven breeds used for field testing - Brahman, Santa Gertrudis, Droughtmaster, Limousin, Hereford, Brangus and Belmont Red - the test's accuracy in picking a true polled animal was about 90 percent.
Dr Burrow said if the results were replicated in wider cattle populations, the test would be very useful for industry. However the test was not perfect, and producers using it would be encouraged to report anomalies to the research team, to allow further refinement.
By participating in the project, producers would have the opportunity to increase their information on the genotype of their animals, as well as help 'road test' a technology that may ultimately help breed-out horns from the northern herd.
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