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ARS Home » Southeast Area » Booneville, Arkansas » Dale Bumpers Small Farms Research Center » Research » Publications at this Location » Publication #398052
Research Project: Sustainable Small Farm and Organic Grass and Forage Production Systems for Livestock and Agroforestry

Location: Dale Bumpers Small Farms Research Center

Title: How does selection for parasite resistance in Katahdin sheep affect other important traits?

Author
item Burke, Joan
item LEWIS, RON - University Of Nebraska
item NOTTER, DAVID - Virginia Tech

Submitted to: Eastern Alliance for Production Katahdins Newsletter
Publication Type: Popular Publication
Publication Acceptance Date: 10/3/2022
Publication Date: 10/16/2022
Citation: Burke, J.M., Lewis, R., Notter, D.R. 2022. How does selection for parasite resistance in Katahdin sheep affect other important traits?. Eastern Alliance for Production Katahdins Newsletter. October 2022.

Interpretive Summary: Genetic selection of sheep for resistance to gastrointestinal nematodes (GIN) has become a priority for pasture-based production of lambs to minimize the need for deworming, but little is known on effects on other traits of economic importance. Scientists from USDA, ARS, Booneville, AR, University of Nebraska and Virginia Tech report that parasite resistance traits at weaning are negatively (favorably) correlated with growth, and moderately correlated with reproduction traits which are thought to be of little consequence. Forward progress on traits important to producers can be made through proper selection. These findings on sheep are important to veterinarians, geneticists, extension specialists, and farmers.

Technical Abstract: Katahdin producers who use NSIP estimated breeding values (EBV) to make selection decisions on replacements for the home flock or for sale often select for more than one trait at a time. In fact, most breeders search for the perfect animal with balanced EBV, or those that excel in all traits of interest. But what happens when two or more traits are used in selection? Can forward progress be made on both traits? Maybe. The "tensions" among the traits, especially between maternal performance and parasite resistance are too low to anticipate that selection for any of the traits will inevitably produce large declines in EBV for any correlated traits. Undesirable genetic correlations are small and manageable. They will slow genetic progress in any one trait but still allow genetic improvement across the full suite of traits.