395V Poster Online - Virtual Posters
Tuesday June 07, 11:00 AM - 3:00 PM

Authors:
Mohammed Sallam ¹; Heather McCormack ²; Bob Fleming ²; Peter Wilson ²; Björn Andersson ³; Matthias Schmutz ³; Cristina Benavides ⁴; Nazaret Dominguez-Gasca ⁴; Estefania Sanchez-Rodriguez ⁴; Alejandro Rodriguez-Navarro ⁴; Ian Dunn ²; Dirk Jan de Koning ¹; Martin Johnsson ¹

Affiliations:
1) Swedish University of Agricultural Sciences, 75651 Uppsala, Sweden; 2) Roslin Institute, University of Edinburgh, Edinburgh EH25 9RG, Scotland, UK; 3) Lohmann Breeding, 7454 Cuxhaven, Germany; 4) Departamento de Mineralogía Y Petrologia, Universidad de Granada,18002 Granada, Spain

Keywords:
Complex traits

Most laying hens display a high tendency to suffer from bone damage (deviations or fractures) either on legs or keels, which is one of the major welfare challenges in the egg production industry. The problem seems to have increased over time from ~30% of commercial layers with at least one bone fracture (Gregory & Wilkins, 1989) up to ~70% of keel bone fractures (Thøfner et al., 2021). To better understand bone health in these breeds, (Dunn et al., 2021) performed detailed bone phenotyping (~55 traits), including measurements for medulla and cortex separately in addition to the whole bone strengths, egg production, and body weights.
Here, we present preliminary results from a genome-wide association study aiming to find genetic marker associations with 47 bone measurements in a cohort of 924 Rhode Island Red laying hens. Hens were killed at 68 weeks of age, weighted, and bone samples were collected including humerus, tibia, and keel bone for further measurements as described in detail in (Dunn et al., 2021). The measurements included: tibia cortical lipid (determined by infrared spectroscopy at main peak 1710 cm^-1), tibia cortical mineral (determined by thermogravimetric analysis, represents salts of Ca and PO4 and some CO3 substitution of the PO4), and medullary bone score (on a scale of 0-3 where 0 represents no medullary bone and 3 a diaphyseal medullary cavity filled with bone). For genome-wide association studies, the hens were genotyped on 57,636 single nucleotide polymorphisms using the Illumina Infinium assay. The genotyping was performed by the SNP&SEQ Technology Platform, Uppsala University, Sweden. For GWAS, we used the linear mixed model implemented in GEMMA version 0.98.5.
Three traits showed associations with p-value < 10^-5: tibia cortical lipid (on chromosomes 2 and 3), medullary bone score (on chromosome 9), and tibia cortical mineral% (on chromosome Z). This study demonstrates the importance of developing bone measurements that enable large-scale genetic mapping studies and genomic selection of bone traits.

References
Dunn, I. C., De Koning, D.-J., McCormack, H. A., Fleming, R. H., Wilson, et al. (2021) 53(1): 11. https://doi.org/10.1186/s12711-021-00603-8
Gregory, N. G., & Wilkins, L. J. (1989) British Poultry Science 30(3):555–562. https://doi.org/10.1080/00071668908417179
Thøfner, I. C. N., Dahl, J., & Christensen, J. P. (2021) PLOS ONE, 16(8):e0256105. https://doi.org/10.1371/journal.pone.0256105