Location: Dale Bumpers Small Farms Research CenterTitle: Genome-wide association study to identify genetic loci associated with gastrointestinal nematode resistance in Katahdin sheep
|BECKER, GABRIELLE - University Of Idaho|
|DAVENPORT, KIM - University Of Idaho|
|LEWIS, RON - University Of Nebraska|
|MILLER, JAMES - Louisiana State University|
|MORGAN, JAMES - Katahdin Hair Sheep International|
|NOTTER, DAVID - Virginia Tech|
|MURDOCH, BRENDA - University Of Idaho|
Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2019
Publication Date: 1/6/2020
Citation: Becker, G.M., Davenport, K.M., Burke, J.M., Lewis, R.M., Miller, J.E., Morgan, J.L., Notter, D.R., Murdoch, B.M. 2020. Genome-wide association study to identify genetic loci associated with gastrointestinal nematode resistance in Katahdin sheep. Animal Genetics. https://doi.org/10.1111/age.12895.
Interpretive Summary: Resistance to gastrointestinal nematodes has previously been shown to be a moderately heritable trait in some breeds of sheep, but the mechanisms of resistance are not well understood. Scientists from University of Idaho, Agricultural Research Service - Booneville, AR, University of Nebraska-Lincoln, Louisiana State University, Katahdin Hair Sheep International, and Virginia Tech used genomic techniques identifying potential sites on genes (chromosomes 2, 3, 16, and 23) associated with resistance to barber pole worm (a voracious blood sucking round worm) in Katahdin sheep. This information is important to sheep producers, scientists, veterinarians, and extension specialists aiming to minimize parasite problems in sheep.
Technical Abstract: Resistance to gastrointestinal nematodes has previously been shown to be a moderately heritable trait in some breeds of sheep, but the mechanisms of resistance are not well understood. Selection for resistance currently relies upon faecal egg counts (FEC), blood packed cell volume, and FAMACHA anaemia scoring phenotypic markers. Identifying genomic markers associated with disease resistance would potentially improve the selection process and provide a more reliable means of classifying and understanding the biology behind resistant and susceptible sheep. A genome-wide association study (GWAS) was conducted to identify possible genetic loci associated with resistance to Haemonchus contortus in Katahdin sheep. Forty animals were selected from the top and bottom ten percent of estimated breeding values for FEC from a total pool of 641 sires and ram lambs. Samples were genotyped using the Applied BiosystemsTM AxiomTM Ovine Genotyping Array (50K) consisting 51,572 single nucleotide polymorphisms (SNP). Following quality control, 46,268 SNPs were included in subsequent analyses. Analyses were conducted using a linear regression model in PLINK v1.90 and a single-locus mixed model in SNP and Variation Suite. Using linear regression, loci on chromosomes 2, 3, 16, and 23 were significantly associated at the genome level with FEC estimated breeding values, and we identified a single region on chromosome two that was significant using both statistical analyses. We suggest a potential role for the gene DIS3 like 3'-5' exoribonuclease 2 for gastrointestinal nematode resistance in Katahdin sheep, although further research is needed to validate these findings and elucidate the mechanisms involved.