A DYNAMIC DETERMINISTIC MODEL TO EVALUATE BREEDING STRATEGIES UNDER MIXED INHERITANCE

A dynamic deterministic model is proposed to study the combined use of an identified major gene and performance information for selection of traits expressed in one sex. The model considers simultaneously combi ned adult selection via within genotype thresholds, mating structures according to major genotypes and preselection of young males. The appl ication given indicates that an optimum combination between performanc es and genotypic information yields better results, in terms of polyge nic means, genotype frequencies and cumulated discounted genetic progr ess, than classical selection ignoring the genotype information. The g reatest advantage of combined selection occurs for rare recessive alle les of large effect on phenotypes (up to +49 % for polygenic gains; +2 6 To for total genetic gain). Optimum within genotype proportions of s elected individuals and mating structures vary with generations thus h ighlighting the value of adynamic approach. (C) Inra/Elsevier, Paris.