More to the Story of Mapping the Cow Genome

Work still remains to be able to use cow mapping.

Published on: May 12, 2009

Although the entire bovine genome is mapped now, that map doesn't have all the information filled in.
Scientists now have a complete picture of how the genome is arranged, but they don't know all relationships between the gene variations and the traits they control.

It's a bit like having a series of relatively detailed maps of the United States, but without a clear understanding of which maps adjoin one another, says Dorian Garrick, Iowa State University geneticist.
At last week's Beef Improvement federation meeting in Sacramento, geneticists repeatedly said they still lack identification of many markers for important traits. Progress is being made, but they are anticipating another leap in technology within this year.

These scientists said the much anticipated release of the 300,000-SNP chip will advance testing for the location of genes controlling desirable traits. SNPs are single nucleotide polymorphisms, which are the measurable and now mapped variances in the genetic code. Industry lingo calls them "snips."

In the past couple years the 50,000-SNP chip has helped track down significant percentages of genetic variation, such that genetics companies can say their DNA tests can account for 20-40% of the genetic variation in certain traits, such as carcass traits or tenderness or feed efficiency.

Within the year, these genomic scientists collectively said, they think the accuracy of the correlations between SNPs and genetic variations could increase significantly, and very soon they could double, accounting for 60-80% of the variation of some traits.

Yet the entire answer to selecting these traits has not been found, they said.

Further, traits with small heritability need even more testing; therefore the larger testing chips will help with that process this year. It also requires large numbers of animals, therefore large collections of DNA samples to especially to correlate the less heritable traits with the gene sequences.

"The message I've been giving people is this really is going to be a revolution," said Mike Goddard, a geneticist with the University of Melbourne and DPI Victoria, Australia. "I know we've been promising you this for years and not delivering, and I'm acutely aware of our failure, but you just got to look at what's happening in dairy to know that this is working now. The whole world's dairy breeding programs are switching over to genomics with dramatic change of their structure of their progeny testing and everything else."

Goddard added that this technology is rapidly nearing a level of viability which could make it a disruptive technology and put those who use it years and dollars ahead of their competitors.