Cow Genome Decoded -- Cheaper Beef for Everybody?

John Roach
for National Geographic News

April 23, 2009

The humble cow has now had its entire genome sequenced, a new study says.

Six years in the making, the feat could lead to healthier, cheaper beef and milk, according to scientists.

A genome is the full set of genes that gives rise to a particular species. Genes are combinations of chemical "letters" that determine animals' and plants' physical traits, from hair color to body shape.

Using the newly decoded cow genome, "you are going to be able to predict an animal's performance on the basis of its [genetic makeup]," biologist Harris Lewin said.

Cow breeders should be able to identify genes responsible for desirable traits and match cows to produce calves with those traits.

This "genomic selection" should enable breeders to raise cows that require less feed and produce lean meat, for example.

Less feed means lower costs for farmers—savings that presumably would be passed on to the consumer.

These improvements, Lewin added, will be important, in part because people in the developing world are likely to eat more meat as their standards of living rise, driving up demand for beef.

"There're some societies that exist primarily on meat and dairy products. It's just part of the culture," said Lewin, who led two research teams on the sequencing project and wrote a commentary on the results, to be published in tomorrow's issue of the journal Science.

Green Meat Never Sounded So Good

Genome-informed breeding could also be good for the environment, Lewin said.

"Just dealing with feed efficiency will help reduce greenhouse gases"—for example, by lessening cow burps, which encourage global warming—"and provide more food for human populations," he said.

(Related blog post: "Fish Oils Reduce Greenhouse Gas Emissions From Flatulent Cows.")

Genomic selection could also make cattle healthier by helping to fight ailments such as mad cow disease.

Breeders should be able to more effectively "breed out" such diseases over generations—and breed in genes identified as disease resistant, Lewin said.

Cow Evolution

The cow genome is also a window into what makes a cow a cow, including which genes give rise to a four-chambered stomach or protein-heavy milk.

Using the deciphered cow genome, scientists compared the genes of several breeds to paint a picture of cattle evolution.

Cattle were domesticated from aurochs—large, extinct European wild oxen—about 10,000 years ago and maintained a diverse ancestral population, the study shows.

Recent selective breeding for agriculture has rapidly reduced that diversity by propagating more of certain breeds and less of others. The trend could be amplified as the deciphered genome allows for even more precise breeding.

This could be of concern to animal breeders because species with low genetic diversity tend to be more vulnerable to disease and inbreeding, the study noted.

But the study also found but that the level of diversity is still on par with the human population, said Curt Van Tassell, a research geneticist with the U.S. Department of Agriculture in Baltimore, Maryland, and study co-author.

"So I think we are still in very good shape," he said. "And beyond that, the tools that this technology gives us allow us to manage diversity at a whole new level. ... I think the outlook is quite bright."