2009-Kim_et_al - Refined mapping of twinning-rate...

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E.-S. Kim, X. Shi, O. Cobanoglu, K. Weigel, P. J. Berger and B. W. Kirkpatrick analysis of insulin-like growth factor-1 as a positional candidate gene Refined mapping of twinning-rate quantitative trait loci on bovine chromosome 5 and doi: 10.2527/jas.2008-1252 originally published online November 7, 2008 2009, 87:835-843. J ANIM SCI http://jas.fass.org/content/87/3/835 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 October 11, 2011 jas.fass.org Downloaded from
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ABSTRACT: Twinning in cattle is a complex trait that is associated with economic loss and health issues such as abortion, dystocia, and reduced calf survival. Twinning-rate QTL have been detected previously on BTA5 in the North American Holstein and Norwegian dairy cattle populations and in a USDA herd selected for high twinning rate. In previous work with the North American Holstein population, the strongest evidence for a QTL was obtained from analysis of an extended, multiple-generation family. Using additional animals, an increased density of SNP marker association tests, and a combined linkage and linkage disequilibrium mapping method, we refined the position of this QTL in the North American Holstein population. Two sets of twinning-rate predicted transmitting abilities estimated during 2 different time periods in the North American dairy cattle population were used to provide validation of results. A total of 106 SNP and 3 microsatellites were used to scan the genomic region between 5 and 80 Mb on BTA5. Combined linkage-linkage disequilibrium analysis identified significant evidence for QTL within the 25- to 35-Mb and 64- to 70-Mb regions of BTA5. The IGF-1 gene ( IGF1 ) was examined as a positional candidate gene and an SNP in intron 2 of IGF1 was sig- nificantly associated with twinning rate by using both data sets ( P = 0.003 and P = 1.05 × 10 −6 ). Replication of this association in other cattle populations will be required to examine the extent of linkage disequilib- rium with the underlying quantitative trait nucleotide across breeds. Key words: bovine, cattle, insulin-like growth factor-1, ovulation, twin ©2009 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2009. 87:835–843 doi:10.2527/jas.2008-1252 INTRODUCTION Twinning in cattle is a complex trait that is associat- ed with the health and productivity of animals. Twin- ning has been associated with economic losses such as abortion, dystocia, reduced birth weights, and reduced neonatal calf survival (Markusfeld, 1987; Fricke and Wiltbank, 1999; Karlsen et al., 2000). Heritability of twinning rate is low (h 2 = 0.09; Johanson et al., 2001), and application of genetic marker-based selection will be useful in reducing twinning rate. To identify twin- ning or ovulation rate QTL, the inheritance of paternal alleles has been investigated previously within bovine half-sib families. When only linkage mapping was used, confidence intervals for QTL were typically broad (>30 cM) because of a limited number of crossover events in 1 or 2 generations. Twinning or ovulation rate QTL de-
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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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2009-Kim_et_al - Refined mapping of twinning-rate...

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