A quantitative trait locus (QTL) analysis of growth and fatness data from a
three-generation experimental cross between Meishan (MS) and Large White (
LW) pig breeds is presented. Six boars and 23 F1 sows, the progeny of six L
W boars and six MS sows, produced 530 F2 males and 573 F2 females. Nine gro
wth traits, i.e. body weight at birth and at 3, 10, 13, 17 and weeks of age
, average daily gain from birth to 3 weeks, from 3 to 10 weeks and from 10
to 22 weeks of age, as well as backfat thickness at 13, 17 and weeks of age
and at 40 and 60 kg live weight were analysed. Animals were typed for a to
tal of 137 markers covering the entire porcine genome. Analyses were perfor
med using two interval mapping methods: a line-cross (LC) regression method
where founder lines were assumed to be fixed for different QTL alleles and
a half-/full-sib (HFS) maximum likelihood method where allele substitution
effects were estimated within each half-/full-sib family. Both methods rev
ealed highly significant gene effects for growth on chromosomes 1, 4 and 7
and for backfat thickness on chromosomes 1, 4, 5, 7 and X, and significant
gene effects on chromosome 6 for growth and backfat thickness. Suggestive Q
TLs were also revealed by both methods on chromosomes and 3 for growth and
for backfat thickness. Significant gene effects were detected for growth on
chromosomes 11, 13, 14, 16 and 18 and for backfat thickness on chromosome
8, 10, 13 and 14. LW alleles were associated with high growth rate and low
backfat thickness, except for those of chromosome 7 and to a lesser extent
early-growth alleles on chromosomes 1 and and backfat thickness alleles on
chromosome 6.