A Global Search Reveals Epistatic Interaction Between QTL for Early Growth in the Chicken

  1. Örjan Carlborg1,4,
  2. Susanne Kerje1,
  3. Karin Schütz2,
  4. Lina Jacobsson1,
  5. Per Jensen2, and
  6. Leif Andersson1,3
  1. 1Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, S-751 24 Uppsala, Sweden; 2Department of Animal Environment and Health, Section of Ethology, Swedish University of Agricultural Sciences, S-532 23 Skara, Sweden

Abstract

We have identified quantitative trait loci (QTL) explaining a large proportion of the variation in body weights at different ages and growth between chronological ages in an F2 intercross between red junglefowl and White Leghorn chickens. QTL were mapped using forward selection for loci with significant marginal genetic effects and with a simultaneous search for epistatic QTL pairs. We found 22 significant loci contributing to these traits, nine of these were only found by the simultaneous two-dimensional search, which demonstrates the power of this approach for detecting loci affecting complex traits. We have also estimated the relative contribution of additive, dominance, and epistasis effects to growth and the contribution of epistasis was more pronounced prior to 46 days of age, whereas additive genetic effects explained the major portion of the genetic variance later in life. Several of the detected loci affected either early or late growth but not both. Very few loci affected the entire growth process, which points out that early and late growth, at least to some extent, have different genetic regulation.

[Supplemental material is available online at www.genome.org.]

Footnotes

  • 3 Corresponding author.

  • 4 Present address: Roslin Institute, Roslin, Midlothian, EH25 9PS, Scotland.

  • E-MAIL Leif.Andersson{at}bmc.uu.se; FAX +46-18 4714833.

  • Article and publication are at http://www.genome.org/cgi/doi/10.1101/gr.528003.

    • Received June 14, 2002.
    • Accepted December 10, 2002.
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