Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2013
Publication Date: 2/1/2014
Citation: Nonneman, D., Lents, C., Rohrer, G., Rempel, L., Vallet, J. 2014. Genome-wide association with delayed puberty in swine. Animal Genetics. 45(1):130-132.
Interpretive Summary: Gilts comprise a significant portion of breeding females and successful gilt development is critical to overall herd performance and profitability. Nearly 10% of gilts fail to express estrus by 8 months of age and anestrus and failure to return to estrus are the most common reasons for removal from the herd. Failure of gilts to exhibit estrus signs rather than delayed puberty contributes to a substantial number of pigs removed because most impubertal gilts examined at this time have had one or more ovarian cycles. Also, inadequate estrus or puberty detection methods may lead to unnecessary culling. Measurement of age at puberty is labor intensive and impractical for large-scale facilities and identifying markers associated with pubertal age and attainment would greatly contribute to reproductive efficiency and overall fertility in swine. The objective of the current study was to identify genetic markers that were associated with failure to reach puberty by 240 days of age in a research population. Twelve genomic regions were identified that were associated with delayed puberty. Identification of the genes involved and DNA markers to identify animals with delayed puberty or fail to show estrus will allow better management decisions or practices to increase reproductive efficiency of swine herds.
Technical Abstract: An improvement in the proportion of gilts entering the herd that farrow a litter would increase overall herd performance and profitability. A significant proportion (10-30%) of gilts that enter the herd never farrow a litter; reproductive reasons account for approximately a third of gilt removals, with anestrous and failure to conceive the most common reasons for culling. Tools to select gilts for reproductive longevity through genomics or alternative phenotypes would be of great benefit to the producer. Ninety-one gilts that failed to display behavioral estrus by 240 days (cases) and 127 pubertal littermates (controls) were genotyped with the Illumina Porcine SNP60 Beadchip. One hundred and seventy-four SNPs with the most significant associations were genotyped in an additional 86 cases and 103 controls. Twelve of these associations were significant in the final analysis. The most significant (p < 1.5 x 10-14) region associated with failure to attain puberty was on chromosome 4 surrounding the NHLH2 gene. Delayed pubertal development and age at first estrus have been associated with NHLH2 in mice. Because attainment of puberty is a complex trait, identifying genes that affect pubertal age would greatly contribute to our knowledge of reproductive development, as well as, overall fertility.