21 December 2009
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 Discovering new DNA markers is like trying to find a needle in a haystack. But the Beef CRC’s Chief Scientist is confident new strategies now being developed will prove worthwhile for Australian beef cattle producers.
Professor Mike Goddard of the Victorian Department of Primary Industries said when it comes to DNA markers, geneticists have already discovered the genes which are easy to find.
“You could say that we’ve already picked the ‘low-hanging fruit’ when it comes to genetic markers,” said Professor Goddard.
“What DNA marker experiments usually pick up first are genes that have a large size of effect. But unfortunately there are very few of those.”
Professor Goddard said the polled gene which determines whether cattle will grow horns or not is an example of a trait where one gene has a major effect.
“A few genes for tenderness also have a significant effect, but genes for other traits such as growth rate, fertility and feed efficiency are proving harder to identify,” he said.
“It’s not like there is ‘a’ gene which controls feed efficiency. Instead traits like growth rate, carcase and meat quality, feed efficiency and fertility seem to be controlled by hundreds or even thousands of genes which all have a small effect.”
The Beef CRC aims to predict the breeding value of young animals for economically important traits which are otherwise hard to select for.
Dr Goddard says the answer could lie in using new “single nucleotide polymorphism” (SNP pronounced “snip”) chips containing thousands of DNA markers.
These SNP chips are used to find the relationships between DNA markers and traits of economic importance.
Professor Goddard said the Beef CRC is using a range of cattle populations that have been measured for important production traits and genotyping them for markers.
“We’ve used a chip with 50,000 SNPs in a range of cattle populations. This helps us to get a comprehensive picture about the animals’ genetic make-up and how it is associated with key production traits,” he said.
“Beef CRC scientists have discovered a range of DNA markers that are associated with each of the traits but we need to test these markers to see if they work in additional groups of cattle,” Professor Goddard said.
He maintains that if the Beef CRC is to find enough markers that work across all breeds, they need to use a SNP chip with many more markers.
“Within the next six months we could be using a panel capable of genotyping 500,000 SNPs for production traits of interest,” Professor Goddard said.
“That will give us an even clearer picture of which markers are worthwhile pursuing and which aren’t.”
This genetic information, along with commercial company Molecular Breeding Values (MBVs or MPVs) that have been validated, will be incorporated into BREEDPLAN EBVs, using prediction equations that have met thresholds for accuracy and validity.
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For further information contact Margaret Puls, Acting Communications Manager, Beef CRC, 0419 578 356
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