Optimizing Selection on Major Genes
Molecular genetics technology is leading to the discovery of individual genes with large effects for traits of interest in swine. Although the use of such major genes can enhance rates of genetic improvement in the short term, their injudicious use can lead to less response to selection in the longer term. This article describes the development of a method to optimize the use of a major gene in selection. Results show that optimal strategies for selection on the major gene can lead to increased response to selection, in particular for major genes that show dominance. The results imply that major genes can substantially enhance rates of genetic improvement in both the short and long term, provided selection on the major gene is integrated properly within existing selection strategies. Thus, the use of major genes in selection, requires careful formulation of the objectives and strategies for selection. The methods developed in this research provide a framework to formulate such strategies. Further extension of methods to deal with the complexities of practical breeding programs is, however, required.