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Title
Comparison of Different Variance Component Estimation Approaches for MACE: Direct and Bottom-up PC
Fields of Research (FoR) 2008:
Author(s)
Publication Date
2009
Socio-Economic Objective (SEO) 2008
Abstract
Multiple-trait across country evaluation (MACE) is used for international genetic evaluation of dairy bulls. MACE treats records in different countries as different traits. Thus, a sire will get a breeding value for each participating country. Whenever a country makes changes to their national evaluation model, the genetic variance-covariance (VCV) matrix needs to be re-estimated. Estimation of the VCV matrix is a different task. For the Holstein production evaluation, which includes 26 traits, it is not possible to estimate the VCV matrix in a single analysis with the currently available estimation methods and the given time constraints. Hence, the complete matrix is built from analyses of sub-sets. This readily results in a non-positive matrix and a bending procedure (Jorjani et al., 2003) needs to be applied to obtain a positive definite matrix. In addition, the VCV matrix is usually over-parameterized as genetic correlations between countries are generally high.
Publication Type
Conference Publication
Source of Publication
Interbull Bulletin 40: Proceedings of the 2009 Interbull Meeting, v.40, p. 72-76
Publisher
International Bull Evaluation Service
Place of Publication
Uppsala, Sweden
ISSN
1011-6079
HERDC Category Description
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