Genetic architecture of bone strength and composition in White Leghorn laying hens

Background Skeletal issues such as fractures and poor bone quality are increasingly recognized for their negative impacts on animal welfare and the economic challenges they bring to the poultry industry. Previous pedigree-based analyses in White Leghorn laying hens have reported moderate heritabilities for cortical and medullary bone composition traits (ranging from 0.18 to 0.41) and strong genetic correlations (0.69 to 0.90) with tibia breaking strength and density. This study uses genome-wide association studies (GWAS) to identify genetic markers associated with bone strength and composition traits, aiming to advance our understanding of the genetic architecture of bone quality in White Leghorn laying hens. Results We identified a set of markers on chromosome 20 (11.55–12.29 Mb) in strong LD with each other ( r 2 > 0.8), significantly associated with humeral stiffness, and overlapping with humeral strength and tibial cortical thickness. These markers were located within the previously identified QTL on chromosome 20 for bone biomechanical strength and body weight. This region harbors a bone morphogenetic protein 7 gene ( BMP7 ) with a known role in skeletogenesis and growth in chicken. Genetic markers with the strongest suggestive association with organic and mineral contents, and total amount of carbonate in bone mineral MinCO3 1415 in tibia medullary bone were detected on chromosome 1 (173.5–173.6 Mb). This region contains the long non-coding RNA LOC107052041 (LncFAM) , which has previously been mapped within growth-related QTL and its polymorphisms have been associated with body weight and skeletal dimensions in chickens. Finally, more accurate heritabilities were estimated for thermogravimetry measurements of bone compositional traits as compared to infrared spectroscopy, with medullary organic and mineral contents being the most heritable (~0.19) and highly correlated with tibia density (0.7). Conclusions This study identified genomic loci associated with variation in bone quality traits, providing candidates for functional validation and for future evaluation of their potential to improve the prediction of bone strength in laying hens.