Most commonly, improvement of livestock species is accomplished using traditional methods of genetic selection. New discoveries in the field of molecular genetics now allow the isolation and study of specific regions of the genome that influence important traits. Special attention has been focused on those genes that are thought to control the physiological pathways that influence the reproductive ability of our common livestock species. Reproduction is used as both a means to propagate animals within a livestock herd and as a way to facilitate genetic improvement of the herd. Unfortunately, the genetic improvement of reproductive traits using classical methods of genetic selection is severely limited, due to the low heritability and sex-limited nature of these traits. Molecular genetics can be used to determine which animals contain reproduction-specific marker regions. These animals can then be selected for inclusion in a marker assisted selection program.
The purpose of this current study was to investigate the effect of several candidate genes on reproductive performance in swine. Candidate genes were selected for investigation based on previous studies that have shown associations between the gene of interest and reproduction in swine (estrogen receptor alpha) or reproduction in other mammalian species (estrogen receptor beta, paternally expressed gene 1, paternally expressed gene 3). A population of Yorkshire, Large White, and reciprocally crossbred female swine were utilized in this study to investigate the associations between each of these candidate genes and a variety of reproductive tract and litter traits. Associations between genotype and reproductive traits were found for all candidate genes studied. The results of this study allow for a greater understanding of the effects of these genes and will allow researchers to determinate how these genes could be most efficiently utilized to improve reproductive performance in swine.