Cow genome map set to improve Brahman breed – ABC Online

Posted April 18, 2017 07:41:19

She is not the prettiest cow you have ever seen, but she is becoming one of the most important Brahmans in the business.

Elrose Naomi 3492 was 14 years old and had had eight calves when she made the ultimate sacrifice for science.

Now her lung tissue sits in a freezer as the final touches are put on a million-dollar project to sequence her genome.

She is not the first cow to have her DNA pulled apart and its order identified, but she will be the first Brahman, a tropically adapted breed found in Australia's north.

Eight years ago, the DNA of a Hereford cow called Dominette was unpacked and scrutinised by a team of international researchers at a cost of $US52 million.

Now, amid huge technological advances and for a fraction of that cost, Queensland researchers are keen to know more about what makes the northern cattle tick and, more importantly, how to improve it.

It is all part of a project to understand how genes from temperate cattle have influenced important production traits in the modern Brahman breed.

Professor Steve Moore, from the Centre for Animal Sciences, is director of the Queensland Alliance for Agriculture and Food Innovation (QAAFI).

He said northern cattle were not as productive as their southern Bos taurus counterparts.

"Their meat quality is not as good and their meat quality is penalised under MSA [Meat Standards Australia] if they have a hump," he said.

"We have to turn that around. We want to raise the value of the northern herd."

The Sequencing the Legends project, jointly funded by the Department of Agriculture and the University of Queensland, has resulted in the DNA of 50 top Brahman bulls picked apart and sequenced, with genes associated with specific traits being studied.

"We are unpacking the entire DNA sequences of 50 influential animals, then honing in on the genes associated with specific traits in order to capture the best genetics in the Brahman breed," Professor Moore said.

Brahmans are adapted to tropical climates, and there have been more than 300,000 years of separation between Bos indicus cattle such as Brahman and the Bos taurus cattle breeds that are important to temperate production systems.

Up until now, much of the world's genetics research has surrounded the Bos taurus, hence the sequencing of Hereford cow Dominette.

But Professor Moore said understanding the genetics underlying production traits in Australian tropically adapted cattle was essential for further breed development and crossbreeding strategies.

"We hope to improve the predictions and that will be delivered via something like Breedplan," he said.

"We will identify some of the mutations underlying some of the traits, but we're confounded by the fact we're working with the Bos taurus reference genome assembly and we get ambiguous results."

And that is where Elrose Namoi comes in.

Once her complete DNA sequence has been determined, she will become a reference animal for the Brahman breed, allowing the DNA of sequenced Brahman bulls to be "put back together" more accurately.

"We sequence a cow because a cow doesn't have a Y chromosome," Professor Moore said.

"The Y chromosome is a pain, so we try to avoid it. She's got two X chromosomes, which makes the X chromosome easier to assemble.

"Once we have Elrose Naomi sequenced, we'll be able to map those bulls onto the Brahman reference, so we'll hopefully have a complete picture of the majority of the Brahman population in Australia."

Professor Moore said for Australia to remain competitive, the industry had to do better with the animals it had in terms of markets, and that meant quality and productivity.

He said producers would start reaping the benefits of the genomics project through Breedplan within a "couple of years".

Topics: rural, cloning-and-dna, dna, beef-cattle, university-of-queensland-4072

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Cow genome map set to improve Brahman breed - ABC Online