Imprinted Gene Loci as Candidate Targets for Performance Traits in Cattle

Genetic (or ‘genomic’) imprinting, a feature of over 100 mammalian genes, refers to the partial or complete transcriptional silencing of one of the two parentally-inherited alleles that occurs in a parent-of-origin manner. While most genomic imprinting studies have focussed on murine models or human biomedical disorders, there is burgeoning interest in the effects of imprinted loci in domestic livestock species, especially as research has shown that imprinted loci influence several important complex production traits. In addition, recent work has highlighted the evolutionary consequences of imprinting in animal breeding systems, particularly where there are differences in both the intensity of selection for sex-specific production traits and male and female effective population sizes. Consequently, we hypothesise that imprinted loci contribute to heritable variation in bovine performance traits. In the current study, a candidate gene approach was adopted to assess a panel of validated single nucleotide polymorphisms (SNPs) in the bovine orthologs of known imprinted genes and their association with a range of performance traits in 848 progeny-tested Irish Holstein-Friesian artificial insemination sires. The findings from this work, together with the documented biological roles of the candidate bovine imprinted loci examined, suggest that they represent an important reservoir of molecular markers and selection targets in future genetic improvement of dairy and beef cattle populations.