"The second possible explanation is that ruminants and cows are typically found in very large herds, and in these herds there is a greater propensity for disease transmission, so you need to be better equipped to withstand diseases."
These new findings will point the way for future research that could result in more sustainable food production.
Dr Tellam said the US$53 million Bovine Genome Sequencing Project led by the Human Genome Sequencing Centre at Baylor College of Medicine (BCM-HGSC) in Houston, Texas is an example of major achievements that can only be realised by substantial international scientific cooperation.
Using the complete genome sequence from L1 Dominette, the female Hereford cow, scientists also undertook comparative genome sequencing for six more breeds to look for genetic changes.
The resulting bovine HapMap a literal map of genetic diversity among different populations is also published in today's edition of the journal Science.
"Domestication and artificial selection appear to have left detectable signatures of selection within the cattle genome yet the current level of diversity within breeds is at least as great as that found within humans," CSIRO Livestock Industries scientist and one of the project's group leaders, Dr Bill Barendse, said.
The implications of the genome project for the beef and dairy industries are enormous.
"The availability of very large numbers of single nucleotide polymorphisms (DNA changes in the genetic blueprint) has allowed the development of gene chips that measure genetic variation in cattle populations and will allow the rapid selective breeding of animals with higher value commercial traits.
"This technology is quickly transforming the dair
|Contact: Lisa Palu|