Connectedness in Genetic Evaluation

  • J. L. Foulley
  • J. Bouix
  • B. Goffinet
  • J. M. Elsen
Part of the Advanced Series in Agricultural Sciences book series (AGRICULTURAL, volume 18)


The problem of connectedness in genetic evaluation is part of the more general one of “adjusting” for nuisance parameters (e.g., herd x year x season) and of estimating genetic population means (group effects). After a review of approaches to the study of connectedness, its impact is discussed in relation to the type of model used (purely fixed or mixed; with or without genetic group) and to the properties sought from an estimator of genetic merit (unbiasedness vs. mean square error). Consideration of connectedness is especially important in the choice of alternative models. The degree of connectedness is likely to be a factor limiting the effectiveness of adjusting genetic evaluations for sources of bias. A coefficient to assess the degree of connectedness in practice is suggested. This coefficient involves pairs of levels of factors, and it varies between 0 (non-estimability) and 1 (balanced distribution according to the factors involved in disconnectedness). Small numerical examples are given to illustrate theoretical aspects of this problem. Practical applications based on the use of artificial insemination sires to connect herds over space and time are also presented.


Mean Square Error Artificial Insemination Nuisance Parameter Genetic Evaluation Genetic Progress 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1990

Authors and Affiliations

  • J. L. Foulley
    • 1
  • J. Bouix
    • 2
  • B. Goffinet
    • 3
  • J. M. Elsen
    • 2
  1. 1.Station de Génétique Quantitative et AppliquéeInstitut National de la Recherche Agronomique (INRA)Jouy-en-JosasFrance
  2. 2.Station d’Amélioration Génétique des AnimauxINRAToulouseFrance
  3. 3.INRA Laboratoire de BiométrieCastanet-Tolosan CedexFrance

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