Location: Reproduction ResearchTitle: Translational genomics for improving sow reproductive longevity Author
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/19/2016
Publication Date: 7/19/2016
Citation: Ciobanu, D.C., Kachman, S.D., Olson, S., Spangler, M.L., Trenhaile, M.D., Wijesena, H., Miller, P.S., Riethoven, J.J., Lents, C.A., Thorson, J.F., Massey, R., Safranski, T.J. 2016. Translational genomics for improving sow reproductive longevity [abstract]. Journal of Animal Science Supplement. 94 (E-Supplement 5):323-324 (Abstract 0691). Interpretive Summary:
Technical Abstract: Sow reproductive longevity is a composite trait that is expressed throughout life that depends on the potential of females to resume ovarian cyclicity, re-breed, and farrow multiple parities. Approximately 50% of sows are culled annually with more than one third due to poor fertility. Age at puberty (AP), the earliest pre-breeding indicator of reproductive success at first breeding, is positively correlated with weaning-to-estrus interval, can be measured early in life, and has a moderate heritability. Selection for AP is challenging due to labor-intensive phenotype collection. Genomic selection for AP would be a more viable since it will potentially increase the accuracy and phenotypic response to selection. The objective of this study was to identify DNA markers that will predict at weaning, gilts with early age at puberty and superior reproductive longevity, which in turn will reduce culling rates and the cost associated with developing replacement sows. Our central hypothesis is that genetic sources that affect age at puberty also explain important variation in sow reproductive longevity and productivity. To test the hypothesis, using the UNL resource population (n>1,700) we integrated different genome-wide association analyses, genome and RNA sequencing, polymorphism discovery to uncover QTL regions, genes and polymorphisms that could predict age at puberty and reproductive longevity. A Bead Array panel of 56,424 SNPs explained 25.2% of the phenotypic variation in age at puberty in a training set (n = 820). In an evaluation data set consisting of subsequent batches (n = 412), the predictive potential of all the SNPs from the major 1 Mb windows was larger compared to the variance captured by the SNP associated with the largest effects from these windows (12.3% to 36.8% vs. 6.5% to 23.7%). One of the major region identified included AVPR1A, a gene that explained some of the pleiotropic effects previously observed and that could be used for the selection of both age at puberty and reproductive longevity. Genome sequencing of 20 representative sires using Ion Torrent Proton technology provided sources of phenotypic variation outside the limited capability of the Bead Array. The sequencing generated a depth of 16.2 to 29.7X across sires, with an average read length of 165bp and ~180K SNPs discovered with 38% of the SNPs located in known genes. In addition, micro-dissection and RNA sequencing of the Arcuate Nucleus (ARC), a region of the brain that controls puberty, provided expression profile of pre- and post-pubertal gilts subjected to different dietary treatments. Integration of all this knowledge will be evaluated in the commercial populations to better understand and improve expression of puberty and reproductive potential of commercial populations through genomic selection.