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  • Open Access

QTL detection and allelic effects for growth and fat traits in outbred pig populations

  • 1Email author,
  • 2 and
  • 1
Genetics Selection Evolution200436:83

https://doi.org/10.1186/1297-9686-36-1-83

  • Received: 17 February 2003
  • Accepted: 25 September 2003
  • Published:

Abstract

Quantitative trait loci (QTL) for growth and fatness traits have previously been identified on chromosomes 4 and 7 in several experimental pig populations. The segregation of these QTL in commercial pigs was studied in a sample of 2713 animals from five different populations. Variance component analysis (VCA) using a marker-based identity by descent (IBD) matrix was applied. The IBD coefficient was estimated with simple deterministic (SMD) and Markov chain Monte Carlo (MCMC) methods. Data for two growth traits, average daily gain on test and whole life daily gain, and back fat thickness were analysed. With both methods, seven out of 26 combinations of population, chromosome and trait, were significant. Additionally, QTL genotypic and allelic effects were estimated when the QTL effect was significant. The range of QTL genotypic effects in a population varied from 4.8% to 10.9% of the phenotypic mean for growth traits and 7.9% to 19.5% for back fat trait. Heritabilities of the QTL genotypic values ranged from 8.6% to 18.2% for growth traits, and 14.5% to 19.2% for back fat. Very similar results were obtained with both SMD and MCMC. However, the MCMC method required a large number of iterations, and hence computation time, especially when the QTL test position was close to the marker.

Keywords

  • QTL mapping
  • IBD
  • variance component
  • heritability
  • pig

(To access the full article, please see PDF)

Authors’ Affiliations

(1)
Roslin Institute (Edinburgh), Midlothian, EH25 9PS, UK
(2)
Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JT, UK

Copyright

© INRA, EDP Sciences 2004

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