title: Short communication: Validation of two animal models for estimation of genetic trends for female fertility in Norwegian dairy cattle.
abstract: Two animal models were compared with respect to potential bias in genetic trend estimates for female fertility and for their predictive ability. In addition to either a fixed effect for month of first insemination or for month-year of first insemination, the models had fixed effects of age and double insemination and random effects of herd-year and animal. The model with a fixed effect of month of first insemination had a larger positive genetic trend for 56-d nonreturn rate in virgin heifers (0.16% yr), smaller downward bias, and somewhat higher predictive ability. These results demonstrate the importance of verifying models to be used in the calculation of breeding values.
authors.affiliation: Department of Animal Science, Agricultural University of Norway, N-1432 As, Norway. ina.ranberg@ihf.nlh.no
authors.forename: I M
authors.initials: IM
authors.lastname: Andersen-Ranberg
authors.forename: G
authors.initials: G
authors.lastname: Klemetsdal
authors.forename: B
authors.initials: B
authors.lastname: Heringstad
mesh_terms: D000818:Animals; D015982:Bias; D001947:Breeding; D002417:Cattle / Q000235:genetics* / Q000502:physiology; D005260:Female; D005298:Fertility / Q000235:genetics*; D008297:Male; D008957:Models, Genetic; D015233:Models, Statistical; D009664:Norway; D019655:Quantitative Trait, Heritable