Location: Livestock Bio-SystemsTitle: Genome-wide association and identification of candidate genes for age at puberty in swine
Submitted to: BioMed Central (BMC) Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2016
Publication Date: 2/29/2016
Publication URL: http://handle.nal.usda.gov/10113/62001
Citation: Nonneman, D.J., Schneider, J.F., Lents, C.A., Wiedmann, R.T., Vallet, J.L., Rohrer, G.A. 2016. Genome-wide association and identification of candidate genes for age at puberty in swine. BMC Genetics. 17(1):50.
Interpretive Summary: Later age at puberty in pigs is associated with lower lifetime fertility. Gilts that have an earlier age at puberty tend to stay in the herd longer, farrow more litters, give birth to more piglets and have a longer more productive life. Estrus traits of gilts (e.g., duration of estrus) are genetically correlated to adult reproductive phenotypes such as wean-to-estrus interval and sow longevity, making age at first estrus an early indicator trait that can be used to select for favorable adult reproductive performance. Age at puberty is moderately heritable in pigs, but age at first estrus is rarely recorded in pork production due to limitations of labor costs and time. Traits that are typically not recorded, observed in only one sex, or are only measured in adulthood, but are critical for important selection decisions early in life, are ideal candidates for marker-assisted selection. With the development of a commercially available, high-density SNP array for pig, the identification of genes and pathways affecting age at puberty of swine is feasible. The objectives of this study were to use high-density genotyping and genome-wide association analysis to identify chromosomal regions and genes influencing age at puberty in pigs. Several of the loci identified in this study have a physiological role for the onset of puberty in rodents, cattle and pigs and a genetic basis for sexual maturation in humans. Because age at puberty is not routinely measured or selected for in commercial herds, and is a predictive factor for sow longevity and lifetime productivity, these genomic markers will facilitate the use of genomic or marker-assisted selection to improve these traits.
Technical Abstract: Reproductive efficiency has a great impact on the economic success of pork production. Gilts comprise a significant portion of breeding females and gilts that reach puberty earlier tend to stay in the herd longer and be more productive. About 10 to 30% of gilts never farrow a litter and the most common reasons for removal are anestrus and failure to conceive. Puberty in pigs is usually defined as the female’s first estrus in the presence of boar stimulation. Genetic markers associated with age at puberty will allow for selection for age at puberty and traits correlated with sow lifetime productivity. Gilts (n = 759) with estrus detection measurements ranging from 140-240 days were genotyped using the Illumina PorcineSNP60 BeadChip and SNP were tested for significant effects with a Bayesian approach using GenSel software. Of the available 8,111 putative QTL, 27 were found to be statistically significant (P < 0.01). Ten QTL were found to be statistically significant at the P < 0.005 level. Two QTL, one on SSC12 at 15 Mb and the other on SSC7 at 75 Mb, explained 16.87% of the total QTL variance. The most compelling candidate genes in these two regions included the growth hormone gene (GH1) on SSC12 and PRKD1 on SSC7. Several loci confirmed associations previously identified for age at puberty in the pig and loci for age at menarche in humans. Several of the loci identified in this study have a physiological role for the onset of puberty and a genetic basis for sexual maturation in humans. Understanding the genes involved in regulation of the onset of puberty would allow for the improvement of reproductive efficiency in swine. Because age at puberty is a predictive factor for sow longevity and lifetime productivity but not routinely measured or selected for in commercial herds, it would be beneficial to be able to use genomic or marker-assisted selection to improve these traits.