Empirical PROPERTIES of solutions from Henderson's mixed model equations when sires are non-randomly used across contemporary groups

Roberto CARVALHEIRO[1],[2]

Flávio Schramm SCHENKEL[3]

Luiz Alberto FRIES2,[4]

Sandra Aidar de QUEIROZ[5]

Stephen Paul MILLER3

§    ABSTRACT: Stochastic simulations were carried out to investigate empirical properties of solutions from Henderson's Mixed Model Equations (HMME) under four different situations (ST1 to ST4) of sire by contemporary group (CG) association. Sires were used across CGs independently of their true breeding values (TBV) in ST1 and according to their TBV in ST2 to ST4, generating mean genetic differences between CGs in these latter situations. HMME were applied under a model including CG as fixed and sire and dam as random effects (M1). Three alternative models were used (M2 to M4). CG, sire, and dam were assumed as random effects in model M2, and as fixed effects in M3. For model M4, CG and sire were assumed as fixed and dam as random effect. Models M1, M2, and M4 showed similar results for situation ST1, whereas model M3 provided solutions with higher mean square error. In the presence of mean genetic differences between CGs, solutions from model M1 were biased. The bias reduced the ability of model M1 in properly ranking animals and its efficiency in selecting genetically superior sires. For situations ST2 to ST4, model M4 showed, in general, better properties than the other studied models.

§    KEYWORDS: Bias, BLUP, genetic evaluation, mixed model

 



[1] Faculdade de Ciências Agrárias e Veterinárias – FCAV, Universidade Estadual Paulista – UNESP, CEP: 14884-900, Jaboticabal, São Paulo, Brasil (Pós-doutorando no Departamento de Zootecnia). E‑mail: rcar@fcav.unesp.br

[2] GenSys Consultores Associados S/S, Porto Alegre, RS, Brasil. Site: www.gensys.com.br

[3] Department of Animal and Poultry Science, Centre for Genetic Improvement of Livestock, University of Guelph, N1G 2W1, Guelph, Ontario, Canada. E‑mail: schenkel@uoguelph.ca / miller@uoguelph.ca

[4] Lagoa da Serra Ltda., Sertãozinho, SP, Brasil. Site: www.lagoa.com.br

[5] Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias – FCAV, Universidade Estadual Paulista – UNESP, CEP: 14884-900, Jaboticabal, São Paulo, Brasil. Email: saquei@fcav.unesp.br