Genome-wide QTL mapping results for regional DXA body composition and bone mineral density traits in pigs

Abstract

Abstract. In a previous study, genome-wide mapping of quantitative trait loci (QTL) for five body composition traits, three bone mineral traits and live weight was performed using whole-body dual-energy X-ray absorptiometry (DXA) data. Since QTL for bone mineral traits were rare, the current study aimed to clarify whether the mapping results were influenced by the analysed body regions. Thus, the same material (551 pigs) and methods as in the whole-body QTL mapping study were used. However, for evaluation of the DXA scans, we manually defined two body regions: (i) from the last ribs to the pelvis (A) and (ii) including the pelvis and the hind limbs (P). Since live weight was not affected by the regional analysis, it was omitted from the QTL mapping design.Our results show an overall high consistency of mapping results especially for body composition traits. Two thirds of the initial whole-body QTL are significant for both A and P. Possible causes for the still low number of bone mineral QTL and the lower consistency found for these traits are discussed. For body composition traits, the data presented here show high genome-wide Pearson correlations between mapping results that are based on DXA scans with the time-saving "whole-body standard setting" and mapping results for DXA data that were obtained by time-consuming manual definition of the regions of interest. However, our results also suggest that whole-body or regional DXA scans might generally be less suitable for mapping of bone mineral traits in pigs. An analysis of single reference bones could be more useful.

Bridging Gaps in the Agricultural Phosphorus Cycle from an Animal Husbandry Perspective—The Case of Pigs and Poultry

“…Monogastric animal species appeared to have DNA variations contributing to the phenotypic variability of certain P characteristics such as P utilization [27,[61][62][63] and bone mineralization [64,65]. In chicken and quail populations, estimations have shown a considerable heritability of approximately 10% [62,63,66].…”

Genetic variants of major genes contributing to phosphate and calcium homeostasis and their association with serum parameters in pigs

“…Indeed, skeletal disorders such as rickets and osteochondrosis occur in both young piglets with rapidly growing bones and adult pigs, resulting in lameness and culling and thus in economic losses (Stern et al 1995 ; Fukawa and Kusuhara 2001 ). Moreover, bone mineralization is correlated with body weight and body composition (Rothammer et al 2017 ). The bone consists of the protective cortical and the metabolic active trabecular bone, being also the reservoir for calcium (Ca) and phosphorus (P).…”

“Sex” and body region effects on bone mineralization in male pigs

“…DXA showed differences in bone mineralization in pigs, especially pronounced for different body regions and among male sex types. For further studies, it is necessary to evaluate whether a lower or higher BMC or BMD affects the health of male fattening pigs, as has been published in human medicine, where a declining bone mineral density is a surrogate for declining bone strength (Ryan, 1997;Bonnick, 2007).…”

“…Recently published genome-wide association studies by Rothammer et al (2014Rothammer et al ( , 2017 showed that further candidate genes or gene regions were found for whole-body or regional bone mineral traits assessed by using DXA in pigs in vivo. Therefore, genomic analysis and additional BMC or BMD phenotypes can add information in terms of leg health and animal welfare in pigs.…”

“…In human medicine, bone mineral density (BMD) or bone mineral content (BMC) are of major interest in managing osteoporosis (Ryan, 1997). To monitor BMC or BMD dualenergy X-ray absorptiometry (DXA) is widely used (Carter et al, 1992;Ryan, 1997;Tothill, 1995;Tothill andHannan, 2002, 2007). This method is based on the attenuation of two X-ray beams at different energy levels.…”