2010-Bjerre_et_al - Investigation of candidate regions...

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Fredholm D. Bjerre, T. Mark, P. Sørensen, H. F. Proschowsky, A. Vernersen, C. B. Jørgensen and M. Investigation of candidate regions influencing litter size in Danish Landrace sows doi: 10.2527/jas.2009-2274 originally published online January 29, 2010 2010, 88:1603-1609. J ANIM SCI http://jas.fass.org/content/88/5/1603 the World Wide Web at: The online version of this article, along with updated information and services, is located on www.asas.org by guest on June 13, 2011 jas.fass.org Downloaded from
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ABSTRACT: Selection for increased litter size has been one of the main objectives in Danish pig breeding since 1992. This selection has led to an average increase of 0.30 piglets/litter per year for Landrace and York- shire sows, resulting in an average litter size of 15.3 pig- lets born alive in 2007, with an SD of 3.5 piglets. The objective of this study was to investigate differences in identity by state relationships and allele effects associ- ated with litter size across 17 selected microsatellite marker positions on chromosomes 11, 13, and 15. For this purpose, 357 Danish Landrace sows with high and low EBV for litter size were genotyped. An assignment test showed that 91 and 90% of the sows could be as- signed correctly to the group of sows representing high and low EBV, respectively, based on genotype informa- tion. Allele effects were estimated separately for each marker by using deregressed EBV and a linear model that include both a polygenic and an allele effect. The investigated region on chromosome 13 was found to have a greater average identity by state relationship compared with the other regions, indicating that selec- tion has taken place in this region. This is supported by an increased average allele effect of microsatellite alleles in the region. In spite of the apparent increased histori- cal selection pressure on chromosome 13, fairly large variation in allele effects was observed, indicating that the markers within the region may be used for mark- er-assisted selection. However, substantial variation in allele effects was observed for several markers on all 3 investigated chromosomes, indicating that selection should preferably be based on several markers. Key words: estimated allele effect, identity by state relationship, litter size, pig, quantitative trait locus ©2010 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2010. 88:1603–1609 doi:10.2527/jas.2009-2274 INTRODUCTION Litter size is an important trait in the swine indus- try. It has been part of the selection objective for the 2 maternal breeds (Landrace and Yorkshire) in the Dan- ish nucleus breeding program since 1992. Selection for litter size has led to an average improvement of 4.6 piglets/litter since 1992 for the purebred Landrace and Yorkshire, resulting in an average litter size of 15.3 pig- lets born alive, with an SD of 3.5 (unpublished 2008 data from Danish Pig Production, Copenhagen).
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This note was uploaded on 01/26/2012 for the course ECON 2272 taught by Professor Gay during the Spring '08 term at Birmingham-Southern College.

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2010-Bjerre_et_al - Investigation of candidate regions...

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