title: Variance component and breeding value estimation for genetic heterogeneity of residual variance in Swedish Holstein dairy cattle.
abstract: Trait uniformity, or micro-environmental sensitivity, may be studied through individual differences in residual variance. These differences appear to be heritable, and the need exists, therefore, to fit models to predict breeding values explaining differences in residual variance. The aim of this paper is to estimate breeding values for micro-environmental sensitivity (vEBV) in milk yield and somatic cell score, and their associated variance components, on a large dairy cattle data set having more than 1.6 million records. Estimation of variance components, ordinary breeding values, and vEBV was performed using standard variance component estimation software (ASReml), applying the methodology for double hierarchical generalized linear models. Estimation using ASReml took less than 7 d on a Linux server. The genetic standard deviations for residual variance were 0.21 and 0.22 for somatic cell score and milk yield, respectively, which indicate moderate genetic variance for residual variance and imply that a standard deviation change in vEBV for one of these traits would alter the residual variance by 20%. This study shows that estimation of variance components, estimated breeding values and vEBV, is feasible for large dairy cattle data sets using standard variance component estimation software. The possibility to select for uniformity in Holstein dairy cattle based on these estimates is discussed.
authors: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, 750 07 Uppsala, Sweden; Statistics Unit, School of Technology and Business Studies, Dalarna University, 791 88 Falun, Sweden.
authors: L
authors: L
authors: Rönnegård
authors: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, 750 07 Uppsala, Sweden; Statistics Unit, School of Technology and Business Studies, Dalarna University, 791 88 Falun, Sweden.
authors: M
authors: M
authors: Felleki
authors: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, 750 07 Uppsala, Sweden.
authors: W F
authors: WF
authors: Fikse
authors: Animal Breeding and Genomics Centre, Wageningen UR Livestock Research, PO Box 65, 8200 AB Lelystad, the Netherlands; Animal Breeding and Genomics Centre, Wageningen University, PO Box 338, 6700 AH, Wageningen, the Netherlands.
authors: H A
authors: HA
authors: Mulder
authors: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, 750 07 Uppsala, Sweden.
authors: E
authors: E
authors: Strandberg
mesh_terms: D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics*; D002452:Cell Count; D004777:Environment; D005260:Female; D018740:Genetic Heterogeneity; D007774:Lactation / Q000235:genetics; D008892:Milk / Q000166:cytology; D008957:Models, Genetic; D015233:Models, Statistical; D010641:Phenotype; D019655:Quantitative Trait, Heritable