Click photo to enlarge
For 10 years, AgResearch Invermay scientist Dr John McEwan
has been part of an international team mapping the cow
genome. Photo by Jane Dawber.
A $US53 million ($NZ95 million) study of the cattle
genome, released today, will lead to greater feed efficiencies
and could help deal with the dairy industry's methane
problem. Mark Price reports.
Humans are more like cows than rodents.
That is just one of the more startling conclusions from a
10-year international study of the bovine genome.
But for Dunedin AgResearch scientist Dr John McEwan, who has
been closely involved in the project throughout, there are
far more immediate, and valuable, implications in the $US53
million study of 500 cattle in 19 countries.
Dr McEwan told the Otago Daily Times yesterday that the work
would speed up the introduction of improved traits in cattle,
and the New Zealand dairy industry was already making use of
the genetic information.
"Initially, it's going to improve the production of the
traits that dairy farmers are interested in, which are the
amount of production and the amount of protein relative to
the amount of fat.
"But longer term, I think it's going to be used for a whole
lot of difficult traits that they can't really address very
well now."
As an example, Dr McEwan used the efficiency of cows to turn
feed into product.
"Up until now, people haven't been able to measure intake on
enough animals, so what they have been doing is saying,
`Well, how much product is this animal putting out and how
heavy is it?' And that's all they use.
"But there are quite big experiments going on now in New
Zealand to measure the feed intake and its conversion
efficiency through into product."
He said the only way they could apply that to the industry
was by using the SNPs, or single nucleotide polymorphisms,
which were identified in the study.
SNPs are responsible for most genetic variations.
Part of the study looked at antimicrobials produced in cattle
saliva, and Dr McEwan believed that was an area with
potential for improving the nutrition of milk and in dealing
with methane.
"Downstream from this, it is going to provide us with the
tools to start to explore how ruminants control digestion of
grass and also potentially factors that influence the
production of methane between individuals."
Asked if there might be increased dangers in the ability to
more quickly alter the genetic make up of cattle, Dr McEwan
said that ability was simply a tool.
"They can be used for good or bad, but historically the
problem has been that often we knew we could do things a lot
better, but we couldn't really do anything because we didn't
have the facilities available."
The study shows that the planet's 1.2 billion cattle each
have more than 22,000 genes, compared with 30,000 for humans.
Cattle had been around for 60 million years.
Domestication, which began 8000 to 10,000 years ago, had
resulted in 800 breeds but led to much less diversity.
Dr McEwan believed the genome work would allow for diversity
in cattle to be retained while "genetic progress" continued.
A consortium of AgResearch, Dairy Insight and Agritech
Investments, invested $US1 million in the project which began
in 2003 and New Zealand Friesian, Jersey, Angus and Hereford
breeds had been used in the study.
Dr McEwan believed New Zealand had benefited from an early
decision to map the genome of cattle rather than pigs.
Two papers on the work are being published in the scientific
journal Science today.
Scientists used an "Oxford grid" to compare the chromosomes
of cattle and humans and concluded this "reinforced that
human genome organisation is more similar to cattle's than
rodents' because most cattle chromosomes primarily correspond
to part of one human chromosome . . ."
