The Gordon Memorial Lecture: genotype, phenotype, selection and more: improving the skeletal health of laying hens.

1. This review is a comprehensive exploration of the author's work in improving skeletal health in laying hens, focusing on the insights from genetics on nutritional, and environmental factors. It discusses the importance of the large number of disciplines that have contributed to the efforts to tackle bone quality in laying hens, particularly the keel bone.2. The transition from cages to non-cage environments has increased keel bone damage, despite improving overall skeletal health. It is a welfare paradox that improving the hen's environment has often been accompanied by greater skeletal damage.3. The role of genetics has been important in understanding and addressing bone health issues and will be a major factor in their improvement. This includes the identification of specific genes, like cystathionine-β-synthase, which has led to nutritional interventions using betaine supplementation to improve bone quality by targeting the one carbon pathway.4. The role of the timing of puberty and its genetic control is an additional factor in bone health, and new methods of measuring bone density in live birds are now important to monitor potential issues and deliver genetic solutions.5. The review emphasises a multi-faceted approach, combining genetics, nutrition, rearing practices, and housing design is required in order to improve skeletal health and enhance the welfare and sustainable performance in laying hens.