Summary and Implications
New methods for genotyping large numbers of genetic markers have been developed, which are cheaper and faster than previous techniques. Iowa State University researchers helped to develop a tool known as the porcine 60K SNP chip that can genotype 64,232 genetic markers simultaneously in a single pig. Similar SNP chips are available for many other species, including sheep, chicken, cattle and dog. These new chips allow for trait association studies to be conducted using many more genetic markers spread across the genome (known as genome-wide association studies or GWASs). In our lab GWASs were performed for a variety of traits in pigs, sheep, and dogs. In pigs, a number of candidate genetic markers and chromosomal regions were associated with feed intake, average daily gain, body composition (such as 10th rib backfat and loin muscle area), feet and leg structure (such as overall leg action, front and rear leg pasterns), and reproductive traits. Other work in pigs involved looking for duplicated regions of the genome to identify genes that were duplicated, which could impact many traits in the pig. In sheep, chondrodysplasia (a condition in which the legs are malformed and other problems arise) was found to be associated with a group of consecutive markers on one chromosome. SNP chip research in dogs is ongoing to look for genes associated with cryptorchidism (retained testicles). These findings offer a promising list of genetic markers that can hopefully be used in the near future to improve animal production via lowered input costs and reduced incidence of disease.
Iowa State University
Gorbach, Danielle M.; Fan, Bin; Onteru, Suneel K.; Zhao, Xia; Du, Zhi-Qiang; Garrick, Dorian J.; Dekkers, Jack C.M.; and Rothschild, Max F.
"Genome-Wide Association Studies for Important Economic
Traits in Domestic Animals Using High Density SNP Genotyping,"
Animal Industry Report:
AS 656, ASL R2540.
Available at: http://lib.dr.iastate.edu/ans_air/vol656/iss1/61