title: Short communication: validation of estimates of genetic trend in the Norwegian cattle population.
abstract: We examined alternative definitions of herd x year effects in models used to estimates genetic trends for clinical mastitis in Norwegian Cattle. The model with random herd x year effects showed significant bias and clearly overestimated genetic trend. To obtain unbiased estimates of genetic trend for clinical mastitis with this data, herd x year should be defined as fixed. Our results emphasized the importance of validating estimates of genetic trend.
authors.affiliation: Department of Animal Science, Agricultural University of Norway, As, Norway.
authors.forename: B
authors.initials: B
authors.lastname: Heringstad
authors.forename: G
authors.initials: G
authors.lastname: Klemetsdal
authors.forename: J
authors.initials: J
authors.lastname: Ruane
mesh_terms: D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics*; D005260:Female; D008297:Male; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000235:genetics*; D008957:Models, Genetic; D009664:Norway / Q000453:epidemiology; D012044:Regression Analysis