A dynamic deterministic model to evaluate breeding strategies under mixed inheritance

Abstract

A dynamic deterministic model was used to study the combined use of (1) an identified major gene affecting a quantitative trait and (2) performance information in selection programmes for traits expressed in one sex. The model simultaneously considered combined adult selection via within genotype thresholds, mating structures according to major genotypes and preselection of young males. The results showed that an optimum combination between performance and genotype information yielded better results, in terms of polygenic means, genotype frequencies and cumulated discounted genetic gain, than classical selection in which genotype information was ignored. The greatest advantage of combined selection was seen for rare recessive alleles with large effects on phenotype (up to +49% for polygenic gains and +26% for total genetic gain). Optimum proportions of selected individuals within genotype and mating structures varied among generations, highlighting the value of a dynamic approach.