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Doctoral thesis, 2016

Breeding for robust sows

Hong, Thu Le


The overall aim of this thesis was to investigate the possibility to breed for robust sows by improving the leg quality and conformation traits. The specific goals were to estimate the genetic correlations between leg conformation, reproduction and longevity in Swedish and Danish sows; and to identify quantitative trait loci (QTLs) as well as possible causal genes underlying leg conformation traits in pigs. Data on leg conformation traits recorded on young pigs in Sweden and Denmark was used in this thesis. In study 1 and 2, the heritabilities of leg conformation traits and their correlations with reproduction and longevity traits in Swedish Yorkshire pigs were estimated. Heritability estimates for leg conformation traits were relatively low, and higher if estimated with a linear-threshold model compared with a linear model. Good leg conformation was favourably correlated with reproduction in study 1 and with sow stayability in study 2. These findings indicate that breeding for better legs would increase the sow reproductive performance and reduce the risk of being early culled. The genetic correlation between leg conformation, reproduction and longevity were examined in Danish Landrace and Yorkshire pigs (study 3). Heritability estimates were low for leg conformation and low to moderate for longevity traits. Both leg conformation and reproduction traits were favourable correlated with longevity traits, implying the potential of improving longevity by selecting for leg conformation and early reproduction traits. A genome-wide association study was performed (study 4) to identify possible genes affecting leg conformation traits in three Danish pig breeds (Landrace, Yorkshire and Duroc). A number of associated QTL regions and diverse candidate genes indicate the complex genetic background of conformation. These traits might be controlled by several genes involved in different biological processes including bone and skeleton development, muscle and fat metabolism and body growth. Meta-analyses can improve the power to detect QTLs compared with single trait association analysis.


association; gait; locomotion; reproduction; survival; swine; gene mapping; heritability; correlation; genetic

Published in

Acta Universitatis Agriculturae Sueciae
2016, number: 2016:100
ISBN: 978-91-576-8702-9, eISBN: 978-91-576-8703-6
Publisher: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences

Authors' information

Hong, Thu Le
Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics

UKÄ Subject classification

Animal and Dairy Science

URI (permanent link to this page)