Sheep Genome Mapping Complete

February 22, 2008 - With the January announcement of the completion of the virtual DNA map of the sheep genome, the sheep industry has moved one step closer to pinpointing the genetic controls for economically important production traits. This breakthrough will allow more breeding success for improved wool, enhanced carcass quality, increased fertility and the ability to cope with parasites.

The International Sheep Genomics Consortium is a partnership of scientists and funding agencies from the United States, Australia, France, Kenya, New Zealand and United Kingdom who have come together to develop public genomic resources that will help researchers find genes associated with production, quality and disease traits in sheep.

"The main goal of this genomics research is to improve animal health and production traits," explained Noelle Cockett, Ph.D., College of Agriculture dean and vice president for extension and agriculture at Utah State University and the sheep genome coordinator for the United States. "The map is a tool that will increase our efficiency in searching for those genetic components that are so valuable to the sheep producer and to the consumer of our products."

Quantitative genetics has been used for many years in selecting animals for improved production such as growth, yield and efficiency. The addition of genomic technology has the potential to lead to more accurate and rapid change, especially for traits that are difficult to measure like disease resistance, feed efficiency and product quality. Genomic information will also provide the basis for the development of precision management systems. Knowledge of an animal's genotype will allow precise sorting into the optimal production-management environment.

"One of the first and most exciting avenues that will be explored is the possibility of using single nucleotide polymorphism (SNP) to enable whole genome selection for traits important in the overall breeding objective," commented Cockett. "SNPs are small genetic differences that are indicative of the traits that can separate a productive or disease resistant animal from the rest of the flock."

The science team has created the underlying information that will allow a SNP chip to scan the genome for 60,000 variants in a single pass, rather than having to conduct separate tests for each variant. This step will allow sheep producers to select animals based on DNA markers that can indicate useful traits from birth.

"The release of the virtual map is a huge milestone in the worldwide sheep industry," commented Ronnie Green, Ph.D., U.S. Department of Agriculture national program leader and executive secretary for the U.S. interagency working group on domestic animal genomics. "Eventually a map of the sheep genome will offer enormous possibilities for producers who want genetic control of economically important production traits, as well as for disease issues. The day that we will find genetic markers for fiber diameter of wool, meat tenderness or pneumonia is within our sights."

According to Cockett, "The virtual map is the first big step. The next phase is to sequence the sheep genome specifically to fill in gaps that remain in the map and then, when the forthcoming 60K SNP chip is available, run it across U.S. sheep populations to see how accurately the markers work in our sheep."

Investments in genomic technology from gene discovery to sequenced genomes have animal agriculture poised at the threshold of the genetic genomic revolution. Application of new genomic technologies by sheep producers will improve the health, efficiency, sustainability and biosecurity of animal production.

In a meeting with Secretary of Agriculture Ed Schafer, Burdell Johnson, president of the American Sheep Industry Association, requested that sheep genomics funding be a priority for the department.

"It would be a serious setback if American producers were locked out of the advancements in productivity and disease control, which are anticipated to be available through the continued funding of this international consortium," concluded Johnson.

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