Animal Science

Research Article

Power of different F2 schemes for QTL detection in livestock

L. Alfonsoa1 p1 and C. S. Haleya1

a1 Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS


The power for detection of quantitative trait loci (QTL) using marker information was compared in several schemes differing in the mating type and the number of parents involved. An experiment based on an F2 population of fixed size obtained by crossing two lines differing phenotypically for a single trait was simulated, assuming that QTLs could be fixed or segregating in the lines crossed. Different additive and dominant QTL effect values and allele frequencies were considered covering a range of different favourable situations for the detection of the QTL. Comparison was done by regression using flanking marker information. Mating animals at the F1 generation level minimizing relationships was not worse than mating at random or maximizing relationships. The number of parents used affected the power of the experiment when the QTL was segregating in the original crossed lines. Differences in power were mainly related to the number of males from the original line. When the power of the experiment was high as a result of genetic hypothesis assumed, considering several males increased the power. However, when the genetic hypothesis assumed led there to be less power to detect a QTL, the power was higher when fewer males were used.

(Received March 10 1997)

(Accepted July 24 1997)


  • experimental design;
  • QTL detection;
  • statistical power


p1 Present address: Departamento de Producción Agraria, Universidad Pública de Navarra, Campus Arrosadia, 31006 Pamplona, Spain.