Detection of quantitative trait loci for carcass composition traits in pigs

Abstract

<p>Abstract</p> <p>A quantitative trait locus (QTL) analysis of carcass composition data from a three-generation experimental cross between Meishan (MS) and Large White (LW) pig breeds is presented. A total of 488 F2 males issued from six F1 boars and 23 F1 sows, the progeny of six LW boars and six MS sows, were slaughtered at approximately 80 kg live weight and were submitted to a standardised cutting of the carcass. Fifteen traits, <it>i.e</it>. dressing percentage, loin, ham, shoulder, belly, backfat, leaf fat, feet and head weights, two backfat thickness and one muscle depth measurements, ham + loin and back + leaf fat percentages and estimated carcass lean content were analysed. Animals were typed for a total of 137 markers covering the entire porcine genome. Analyses were performed using 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. Additional analyses were performed to search for multiple linked QTL and imprinting effects. Significant gene effects were evidenced for both leanness and fatness traits in the telomeric regions of SSC 1q and SSC 2p, on SSC 4, SSC 7 and SSC X. Additional significant QTL were identified for ham weight on SSC 5, for head weight on SSC 1 and SSC 7, for feet weight on SSC 7 and for dressing percentage on SSC X. LW alleles were associated with a higher lean content and a lower fat content of the carcass, except for the fatness trait on SSC 7. Suggestive evidence of linked QTL on SSC 7 and of imprinting effects on SSC 6, SSC 7, SSC 9 and SSC 17 were also obtained.</p

Detection of quantitative trait loci for teat number and female reproductive traits in Meishan × Large White F2 pigs

“…This result is not exceptional, as the so-called 'cryptic' alleles were also detected for several other traits in this same experiment (Bidanel et al, 2001;Milan et al, 2002) or in many other experiments (Bidanel and Rothschild, 2002). Several hypotheses, such as random drift, selection effects on pleiotropic or linked QTL, or epistatic gene interactions can be proposed to explain this phenomenon.…”

Mapping QTL for growth and muscling traits in three connected porcine F&lt;sub&gt;2&lt;/sub&gt; crosses

“…These QTL were distributed over five confidence intervals (see also the plots of the test statistics in Figure 2). QTL affecting growth and muscling on this chromosome have previously been mentioned in other F 2 cross-studies (Bidanel et al 2001, Milan et al 2002, although the QTL were not always located at the same region as in this study.…”

A genome scan for loci affecting adipocyte size and number in abdominal fat in a White Duroc × Erhualian F2 resource population

“…We observed an interesting phenomenon that the favorable allele decreasing adipocyte size originates from the Erhualian breed at the QTL, which is contrary to the breed characteristic difference in this trait. This observation has been repeatedly documented in many QTL for other traits around this region (Bidanel et al, 2001;Milan et al, 2002;Rothschild et al, 2007). The reason for it remains unknown.…”

“…This region also showed the suggestive effects on adipocyte perimeter and volume ( Figure 1b). As on SSC7, the QTL region associated with adipocyte size on SSC1 corresponds to previously reported QTL for backfat thickness (Rohrer and Keele, 1998;de Koning et al, 1999;Bidanel et al, 2001;Milan et al, 2002;Sanchez et al, 2006). The co-localization of QTL for adipocyte size and backfat thickness shows that there are genetic factors simultaneously affecting the two traits related to fat deposition in those chromosomal regions.…”