Research breakthrough paves way for 'supercow'
The successful sequencing of the cow genome could lead to treatments for malaria and the development of a 'supercow' that thrives in harsh conditions, say Australian researchers.
Researchers involved in the $US52 million international collaboration say the work will revolutionise beef and milk production by giving producers access to cheap tests to assess the genetic quality of stock.
The findings of the project, partly funded by the CSIRO and led by Australian researchers, are published today in two reports in the prestigious journal Science.
More than 300 researchers from 25 countries have spent six years analysing the genome of a female Hereford cow, named L1 Dominette, the first mammalian livestock animal in the world to be sequenced.
While one team focused on the biology of cattle, a second team, the Bovine HapMap Consortium examined genetic diversity among different breeds to look at the evolution and domestication of bovines.
The majority of the sequencing by the Bovine Genome Sequencing and Analysis Consortium was completed at the Baylor College of Medicine in Houston in the US and was led by expatriate Australian, Dr Richard Gibbs.
One of the lead investigators on the project, Dr Ross Tellam, of CSIRO Livestock Industries, says the sequencing found the cattle genome contains a minimum 22,000 genes.
About 14,000 of these are common to all sequenced mammals, which include humans, rodents, dogs, opossums and the platypus, he says.
Dr Tellam says these genes represent the "engine room" of mammalian biology.
However, the cattle genome appears to have been significantly re-organised since its lineage diverged from a common mammalian ancestor about 95 million years ago.
Dr Tellam says this re-organisation has altered genes involved in immunity, reproduction, lactation, digestion and metabolism, when compared with other mammals.
He says in particular, cows seem to have an enhanced ability to fight disease.
The project has major ramifications for the management of domesticated cattle (Bos taurus and Bos taurus indicus), which provide a significant source of milk, meat and clothing to nearly 6.6 billion people worldwide.
Dr Tellam and co-author, Professor David Adelson, of the University of Adelaide, say the genetic sequencing should pave the way for more sustainable and efficient food production.
Readily available genetic testing "will mean livestock producers will not only be able to breed superior animals, but will be able to assess the genetic potential of the animals they have," says Professor Adelson.
The cow genome may also play a role in helping develop medical treatments for human diseases.
For example, says Professor Adelson, cows do not get malaria. By targeting those genes that are found in humans, but not in cows, he says, it "will narrow down" the possible targets for research.
Dr Bill Barendse of CSIRO Livestock Industries, is part of the group that constructed the bovine HapMap, which is outlined in the second Science paper.
The team examined 37,470 differences in the DNA of 497 different cattle from 19 geographically and biologically mixed breeds.
Dr Barendse says they found that while the ancient population size was relatively large, its genetic diversity was reduced by domestication, which began about 10,000 years ago.
So although cattle populations have increased along with the human population, the genetic diversity of those animals has decreased.
He says this had important implications for future management of cattle populations.
"We need to conserve the genetic variability of cows to ensure we have enough [to provide for food] into the future," he said.
The findings may also help maintain beef production as a viable industry in northern Australia.
Dr Barendse says the technology will make it possible to develop a "supercow" that will cope with changes in temperature and rainfall expected to come with climate change.