Australian scientists who helped to sequence the cow genome say it will revolutionise breeding techniques, and lead to more efficient milk and beef production.
Scientists at the CSIRO were among a team of 300 researchers from 25 countries who spent six years mapping and analysing the genetic make-up of a Hereford cow, named L1 Dominette, which lives on a research station in Montana, USA.
The results of the project were published on Friday in the international journal Science.
Some surprises were found buried deep in the bovine's genetic code, says David Adelson, who is professor and chair of Bioinformatics and Computational Genetics at the University of Adelaide.
But the real breakthrough, he says, was the ability to fast-track the meat and dairy industries' efforts to improve their stock, as quickfire DNA testing could replace selective breeding programs that span years.
"I think this is going to have a big impact on the dairy industry," said Prof Adelson.
"Currently what happens is bulls are essentially selected to create better dairy cows.
"It means creating several generations of offspring (and) it takes up to five years before you can settle on one that might be an improvement.
"With a good set of genetic tests you can evaluate the bulls at birth ... you can essentially short-cut those five years."
Similar techniques could help the beef industry produce a cow with a smaller environmental footprint, particularly one that produces less greenhouse gas.
The scientists meticulously mapped the 2,870 billion DNA building blocks that provide the code for the cow's 22,000 genes (about 14,000 of which are common to all mammals, including humans).
Using Dominette's genetic data as a baseline, scientists then did comparison genome sequencing for six more cow breeds to look for variances.
"The (bovine) genome sequence is roughly about three billion pieces of information strung end-to-end, and if you had to type this in a font (size) of 10 it would stretch from Brisbane to Perth and back again," says CSIRO Livestock Industries researcher Dr Ross Tellam.
"To get this sequence together, in the right order, and then to analyse it, is a very major undertaking."
The analysis revealed cows have extra genes dedicated to the operation of their immune system, which gives them the resilience they need to live healthily in herds and with exposure to a wider range of micro-organisms than humans could cope with.
Cows can't catch malaria, and it is hoped a complete understanding of their genetic code will point to possible new treatments for humans.
And when probing the part of the cow's genome sometimes referred to as "junk DNA" - because it plays little direct role in the formation of the creature - it was found that 25 per cent of this genetic code was passed down from a reptilian ancestor.
"It used to be called junk DNA but I don't want to use that term because we now know it's not junk, it can have functions," said Prof Adelson.
"Those (genetic markers) were of reptilian origin. They were laterally transferred at some time in the distant past to the (cow) ancestor, from snakes.
"So we find some surprises in the humble cow ... At every turn we raise more questions than we answer."
The Bovine Genome Sequencing Project cost $US53 million and two major reports are published on Friday in the journal Science.
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