Whole genome scan in chickens for quantitative trait loci affecting growth and feed efficiency.

A feed efficiency experiment was conducted in a population consisting of progeny from 10 full sib families of a cross between two broiler lines. Microsatellite genotypes were determined on Generation (G) 1 and 2. In G3, BW at 23 and 48 d and feed intake were measured and were used to calculate growth between 23 and 48 d, feed intake adjusted for BW, and feed efficiency. Average adjusted progeny trait values were calculated for G2 animals after adjusting phenotypic observations on offspring for fixed effects, covariables, maternal genetic effects, the additive genetic contribution of the mate, and heterogeneity between sexes and were used as dependent variable in the quantitative trait loci (QTL) analysis. A full sib interval mapping approach was applied using genotypes from 420 markers on 27 autosomal linkage groups. Four QTL exceeded significance thresholds. The most significant QTL was located on Chromosome 1 at 235 cM and had a 4% genomewise significance for feed intake between 23 and 48 d. Furthermore, this QTL exceeded suggestive linkage for growth between 23 and 48 d and BW at 48 d. A second QTL was located on linkage group WAU26 at 16 cM and showed suggestive linkage for feed intake between 23 and 48 d. On Chromosome 4, at 147 cM a third QTL, which had an effect on both feed intake traits, was found. Finally, a fourth QTL, which affected feed intake adjusted for BW, was located on Chromosome 2 at 41 cM.