Potential benefit from using an identified major gene in BLUP evaluation with truncation and optimal selection

This study investigates the benefit of including information on an identifi ed major gene in the estimation of breeding values in BLUP selection progra mmes. Selection for a quantitative trait is controlled by polygenes and a m ajor locus with known effect. The benefit of using the gene information obt ained in the short-term was maintained in the long-term by applying a selec tion tool which makes use of BLUP evaluation and optimisation of genetic co ntributions for maximising genetic gain while restricting the rate of inbre eding. In the mixed inheritance model the selection tool, initially propose d for an infinitesimal model, was able to restrict the rate of inbreeding t o the desired value and to give higher rates of response than standard trun cation selection both when using and ignoring the information on the major gene. The simple use of BLUP (standard truncation selection) allowed long-t erm benefits from using the gene in situations where the favourable allele was recessive or additive with large effect. (C) Inra/Elsevier, Paris.