Bovine Genome Provides Clues to Evolution, Better Beef and Milk

Sequencing of the bovine genome provides new information about mammalian evolution as well as cattle-specific biology and points the way to research that could result in more sustainable food production in a world challenged by global population growth.

The future challenge will be to explore the bovine genome sequence in greater depth to fully understand the genetic basis of the evolutionary success of ruminants as this will provide opportunities to address some of the crucial issues of the present time – efficient and sustainable food production for a rapidly increasing human population.

This is the first genome of a mammalian livestock animal that have been studied. Most of more than 25 companion reports describing detailed analyses of the two projects by the Bovine Sequencing Project and the Bovine Hapmap Consortia appear online at www.biomedcentral.com in a special electronic issue of the BioMed Central journal group.

Funding was provided by an international group that included the IAEA, through its Animal Production and Health (APH) Subprogramme of the FAO/IAEA Joint Centre for Nuclear Applications to Food and Agriculture. Specifically, the IAEA sponsored the inclusion in the study of the Sheko breed, which is native to Ethiopia. The Sheko breed is resistant to trypanosomosis and has the ability to achieve good productivity under difficult environmental conditions in Africa. It is hoped that the information obtained from the study can be a first step in the greater utilization of the Sheko and other related indigenous breeds to improve livestock productivity in Africa and, as a result, the livelihoods of farmers. Technical Officers of the APH also contributed to data analysis. A full listing of participants can be found in the article at www.sciencemag.org.

In short: The Bovine Haplotype Map, as it's called, characterizes genetic diversity among breeds. Tens of thousands of single nucleotide-polymorphisms (variations in DNA molecules at a single DNA base) were identified in the genome of a Hereford cow and mapped and characterized in six additional breeds. From there, the team examined the most interesting single nucleotide-polymorphisms (more than 37,000 in nearly 500 cows) with some groups of which diverged evolutionarily more than 250,000 years ago. The researchers found surprisingly high genetic diversity within individual breeds--higher than what's seen in human and dog populations. They also saw different genetic patterns depending on whether the cow was bred to produce meat or milk.

The Bovine Haplotype Map is generating excitement because it offers the chance to select for features that cattle breeders want in their cows -in particular, high-quality milk. Until now, the only way to guarantee the best cow's milk was by taking a bull, inseminating cows with his semen, and then waiting for the female offspring to grow and produce calves and milk to feed them, at a cost of $25,000 to $50,000 per bull. (Most of the genetic improvements in the cattle industry come through males, because each male can produce tens of thousands of females.) Already, cattle breeders are eagerly mapping single nucleotide-polymorphisms in most of their bulls, with an eye toward identifying which single nucleotide-polymorphisms are linked with good milk and other promising qualities.

Related Link: Press Release [pdf]