Mapping of quantitative trait loci on porcine chromosome 4

Abstract

A F2 population derived from a cross between European Large White and Chinese Meishan pigs was established in order to study the genetic basis of breed differences for growth and fat traits. Chromosome 4 was chosen for initial study as previous work had revealed quantitative trait loci (QTLs) on this chromosome affected growth and fat traits in a Wild Boar x Large White cross. Individuals in the F2 population were typed for nine markers spanning a region of approximately 124 CM. We found evidence for QTLs affecting growth between weaning and the end of test (additive effect: 43.4 g/day) and fat depth measured in the mid-back position (additive effect: 1.82 mm). There was no evidence of interactions between the QTLs and sex, grandparents or F1 sires, suggesting that the detected QTLs were fixed for alternative alleles in the Meishan and Large White breeds. Comparison of locations suggests that these QTLs could be the same as those found in the Wild Boar x Large White cross.

Detection of�quantitative trait loci for�carcass composition traits in pigs

“…The SSC 4 QTL had significant or suggestive effects on subcutaneous fat measurements, but did not affect lean deposition. This result was consistent with the available literature results which indicate significant QTL effects for fatness traits in several populations [1,2,6,25,29,36,45]. Significant effects on leanness traits were reported in Wild Boar × Large White [2] and Iberian × Landrace [36] F2 pigs, but not in Meishan × Large White crosses.…”

“…It explained a much larger fraction of the phenotypic variance than SSC 1, SSC 2 and SSC 4 QTL (14 and 24% for backfat and leaf fat weights, respectively, vs. less than 5% for the other 3 QTL). The QTL position and the effects of Meishan alleles are in agreement with the results obtained by Rohrer and Keele [40] on leaf fat weight and those evidenced for backfat thickness in Meishan × Large White crosses by several authors [6,13,39,40,42,44,45,47]. Numerous genes can be proposed as positional candidates in this region which has a high gene density and is highly polymorphic (e.g.…”

“…The effects of this chromosomal region were also evidenced on intramuscular fat content by de Koning et al [13] and Rattink et al [38] and on fatty acid composition by Pérez-Enciso et al [36], who hypothesised that these effects might be pleiotropic effects of the FAT1 locus. Some studies also detected growth QTL in the same chromosomal area [1,6,36,45,47]. Yet, their most likely positions do not exactly coincide with that of FAT1.…”

“…A number of experiments have been set up in pigs to identify quantitative trait loci (QTL) associated with major economically important traits (e.g. [1,13,33,[40][41][42]45]). …”

Mapping of quantitative trait loci and confirmation of the FAT1 region on chromosome 4 in an F2 population of pigs

“…Different QTL have been mapped in several crosses of various breeds, and it is of fundamental interest to know whether similar effects are present in other crosses and, mainly, in commercial populations (Walling et al, 1998). Once the genes and markers have been validated, these data can be used together with traditional methods in marker-assisted selection, to improve the efficiency of breeding programs.…”