Abstract
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 LW boars and six MS sows, produced 530 F2 males and 573 F2 females. Nine growth traits, i.e. body weight at birth and at 3, 10, 13, 17 and 22 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 22 weeks of age and at 40 and 60 kg live weight were analysed. Animals were typed for a total of 137 markers covering the entire porcine genome. Analyses were performed 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 revealed 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 QTLs were also revealed by both methods on chromosomes 2 and 3 for growth and 2 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 2 and backfat thickness alleles on chromosome 6.
Highlights
Genetic maps of the porcine genome have been developed during the last decade [3,10,32,33]
An experiment was conducted at INRA to map loci affecting a number of economically important traits in a Meishan × Large White F2 population using microsatellite markers
A genomewide scan using a panel of 137 markers was performed in a Meishan × Large White crossbred population with 530 males and 573 female F2 progeny
Summary
Genetic maps of the porcine genome have been developed during the last decade [3,10,32,33]. Rothschild, personal communication), spaced throughout the genome, are currently available. These genetic maps have made it possible to perform a systematic search of individual loci affecting quantitative traits of economic importance. An experiment was conducted at INRA to map loci affecting a number of economically important traits in a Meishan × Large White F2 population using microsatellite markers. The large differences observed between both breeds in growth performance, body composition, meat quality, reproduction and behaviour A genomewide scan using a panel of 137 markers was performed in a Meishan × Large White crossbred population with 530 males and 573 female F2 progeny. This paper reports the results obtained for growth rate and backfat thickness
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