Genet. Sel. Evol.
Volume 34, Number 3, May-June 2002
|Page(s)||335 - 352|
Genet. Sel. Evol. 34 (2002) 335-352
Use of maternal information for QTL detection in a (grand)daughter designMarc Bolard and Didier Boichard
Station de génétique quantitative et appliquée, Institut national de la recherche agronomique, 78352 Jouy-en-Josas cedex, France
(Received 17 September 2001; accepted 6 March 2002)
In a (grand)daughter design, maternal information is often neglected because the number of progeny per dam is limited. The number of dams per maternal grandsire (MGS), however, could be large enough to contribute to QTL detection. But dams and MGS usually are not genotyped, there are two recombination opportunities between the MGS and the progeny, and at a given location, only half the progeny receive a MGS chromosomal segment. A 3-step procedure was developed to estimate: (1) the marker phenotypes probabilities of the MGS; (2) the probability of each possible MGS haplotype; (3) the probabilities that the progeny receives either the first, or second MGS segment, or a maternal grandam segment. These probabilities were used for QTL detection in a linear model including the effects of sire, MGS, paternal QTL, MGS QTL and maternal grandam QTL. Including the grandam QTL effect makes it possible to detect QTL in the grandam population, even when MGS are not informative. The detection power, studied by simulation, was rather high, provided that MGS family size was greater than 50. Using maternal information in the French dairy cattle granddaughter design made it possible to detect 23 additional QTL genomewise significant.
Key words: QTL detection / daughter design / granddaughter design / dairy cattle
Correspondence and reprints: Didier Boichard
© INRA, EDP Sciences 2002