A QTL for osteoporosis detected in an F₂ population derived from White Leghorn chicken lines divergently selected for bone index

Abstract

Osteoporosis, resulting from progressive loss of structural bone during the period of egg-laying in hens, is associated with an increased susceptibility to bone breakage. To study the genetic basis of bone strength, an F(2) cross was produced from lines of hens that had been divergently selected for bone index from a commercial pedigreed White Leghorn population. Quantitative trait loci (QTL) affecting the bone index and component traits of the index (tibiotarsal and humeral strength and keel radiographic density) were mapped using phenotypic data from 372 F(2) individuals in 32 F(1) families. Genotypes for 136 microsatellite markers in 27 linkage groups covering approximately 80% of the genome were analysed for association with phenotypes using within-family regression analyses. There was one significant QTL on chromosome 1 for bone index and the component traits of tibiotarsal and humeral breaking strength. Additive effects for tibiotarsal breaking strength represented 34% of the trait standard deviation and 7.6% of the phenotypic variance of the trait. These QTL for bone quality in poultry are directly relevant to commercial populations.

Genetic architecture of bone quality variation in layer chickens revealed by a genome-wide association study

“…This region was similar to a reported QTL for tibia BMD on chromosome 1 in a broiler × layer cross12. Dunn et al 14. reported significant QTL for tibia breaking strength, with the location of the QTL close to the region identified in this study14.…”

“…Dunn et al 14. reported significant QTL for tibia breaking strength, with the location of the QTL close to the region identified in this study14. In another study, where Jungle fowl and White Leghorns were used to set up the resource population, a QTL related to noncortical BMD was reported, with the confidence intervals close to the region identified in this study11.…”

“…Line diversity on bone strength and BMD has been described, possibly associated with body size or egg production89. Until now, only five studies have mapped quantitative trait loci (QTL) to bone traits in chickens101112131415. Six QTL affecting femur BMD have been identified on chromosomes 1, 2, 8, 27 and Z.…”

Differential Gene Expression from Genome-Wide Microarray Analyses Distinguishes Lohmann Selected Leghorn and Lohmann Brown Layers

“…A number of studies showed that LSL layers have lower humerus breaking strengths, but less keel bone deformities than hens of the LB layer line [10],[11]. Dunn et al [12] detected one significant QTL on chromosome 1 for bone index and its component traits of tibiotarsal and humeral breaking strengths in an F2 cross produced from lines of hens that had been divergently selected for bone index from a commercial pedigreed White Leghorn population.…”

Genetic regulation of bone strength: a review of animal model studies

“…50 In a second study, a QTL on chicken Chr 1 for long bone flexural strength was mapped in two white Leghorn lines. 51 However, bone size and shape were not measured in this study, clouding the interpretation of these results. The third study was substantially larger and involved Cobb-Cobb broilers bred to White Leghorn layers.…”