Animal Science, Department of


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Research Report, Animal Science, NPB project #09-032


Used by permission.


Sows are more productive today than ever before. However, concurrent with increased prolificacy, high sow death losses and replacement rates are serious economic and welfare issues facing producers. Reproductive failure is the most frequent reason for culling sows. Length of productive life is moderately heritable and has high variance; thus, substantial genetic variation is expected to exist in most populations. Genetic improvement in the swine industry occurs from selection in nucleus herds and is then transmitted through the breeding pyramid in the multiplication process. Thus, it is critical to identify selection methods that can be applied in nucleus herds that will improve length of productive life in commercial herds. This trait is quite complex and believed to be affected by many genes with relatively small to moderate effects. As a consequence, the response to traditional selection methods is low; generation intervals will be long and accuracy of identifying genetically superior young animals will be reduced. Therefore, this trait is one for which application of genomic tools will be especially helpful. Using genome wide association studies we identified several major and minor loci associated with developmental and sow reproductive traits as well as with sow life-time reproductive and productive traits. As expected, we identified common loci that influence the variation of different traits. For example, same chromosomal regions potentially influence variation of both age at puberty and the lifetime number of live piglets produced by a sow. We are in process of assembling a panel of DNA markers associated with sow reproductive and productive longevity and identify procedures to apply the information in whole genome selection. The markers effects estimated in our population will be validated in other commercial populations and discussions about potential collaborations were initiated with major breeding organizations and commercial producers. We expect that our research will provide a molecular tool that will reduce culling rates, sow death losses, and enhance the productive life of sows.