Detection of quantitative trait loci for fat androstenone levels in pigs1

Abstract

A QTL analysis of fat androstenone levels from a three-generation experimental cross between Large White and Meishan pig breeds was carried out. A total of 485 F2 males grouped in 24 full-sib families, their 29 parents and 12 grandparents were typed for 137 markers distributed over the entire porcine genome. The F2 male population was measured for fat androstenone levels at 100, 120, 140, and 160 d of age and at slaughter around 80 kg liveweight. Statistical analyses were performed using two interval mapping methods: a line-cross (LC) regression method, which assumes alternative alleles are fixed in founder lines, and a half- full-sib (HFS) maximum likelihood method, where allele substitution effects were estimated within each half- and full-sib family. Both methods revealed genomewide significant gene effects on chromosomes 3, 7, and 14. The QTL explained, respectively, 7 to 11%, 11 to 15%, and 6 to 8% of phenotypic variance. Three additional significant QTL explaining 4 to 7% of variance were detected on chromosomes 4 and 9 using LC method and on chromosome 6 using HFS method. Suggestive QTL were also obtained on chromosomes 2, 10, 11, 13, and 18. Meishan alleles were associated with higher androstenone levels, except on chromosomes 7, 10, and 13, although 10 and 13 additive effects were near zero. The QTL had essentially additive effects, except on chromosomes 4, 10, and 13. No evidence of linked QTL or imprinting effects on androstenone concentration could be found across the entire porcine genome. The steroid chromosome P450 21-hydroxylase (CYP21) and cytochrome P450 cholesterol side chain cleavage subfamily XIA (CYP11A) loci were investigated as possible candidate genes for the chromosome 7 QTL. No mutation of coding sequence has been found for CYP21. Involvement of a candidate regulatory mutation of CYP11A gene proposed by others can be excluded in our animals.

Genetic and metabolic aspects of androstenone and skatole deposition in pig adipose tissue: A review(Open Access publication)

“…The first QTL analysis of androstenone levels in fat was performed on a three-generation experimental cross between Large White (LW) and Meishan (MS) pig breeds [33]. The level of androstenone in fat was measured on F2 generation boars aged 100, 120, 140 and 160 days and on individuals slaughtered at around 80 kg live weight.…”

“…In both studies, the power to detect QTL was limited by the size of the populations. The French study [33] included 485 intact males and only one QTL was detected at slaughter. The British study [21] was performed with only 178 boars and authors characterized five androstenone QTL at slaughter.…”

A genome-wide association study on androstenone levels in pigs reveals a cluster of candidate genes on chromosome 6

“…Somewhat lower heritabilities have been reported for skatole, between 0.19 and 0.55 [15,16]. Two linkage studies using microsatellite markers have identified several QTL regions for androstenone and skatole in experimental crosses with 485 and 187 F2 animals, respectively [17,18] pointing towards several areas in the genome affecting these traits. Also, single candidate genes involved in androstenone synthesis and metabolism of androstenone and skatole have been analyzed at the level of RNA and protein expression and in single SNP association studies (reviewed by Robic et al, 2008 [19]).…”

Efficiency of genomic prediction for boar taint reduction in Danish Landrace pigs

“…A more acceptable and practical long‐term approach is the genetic selection of animals against expression of boar taint (Quintanilla et al . 2003; Lee et al . 2005; Moe et al .…”

“…QTL mapping studies and genome‐wide association studies (GWASs) appear to have identified QTL that differ markedly by location and effect (Quintanilla et al . 2003; Lee et al . 2005; Grindflek et al .…”