Fractures to the keel bone is one of the greatest problems facing the laying hen industry. With most severe effects observed in non-cage housing, frequencies are expected to dramatically increase as the industry continues transitioning away from battery cages. Incidences within commercial systems are well documented, where the main cause is believed to be high egg production and the associated need for calcium drawing on endogenous reserves (i.e., bone) leaving bone weakened and prone to fracture. The current work sought to characterize various bone mineral and biomechanical properties of 5 distinct purebred or crossbred laying hen lines (3 commercial: Bovans Brown, Dekalb White, and Institut de Sélection Animale Dual Brown; 2 non-commercial: Experimental Brown and Experimental White), following previous work that demonstrated differences in susceptibility to keel fracture using an ex vivo impact testing apparatus. The keel was then removed to undergo analysis by computer tomography; the humerus and tibia were also removed for biomechanical testing. The keel bone mineral density and moment of area correlated moderately with hen weight and susceptibility to fracture. The biomechanical properties of the tibia, but not the humerus, showed a strong relationship with hen weight. One commercial genetic line (Dekalb White) with a high susceptibility to fracture exhibited a mean tibia strength below the value expected from its mean weight. Our results suggest that for the purebred or crossbred lines other than Dekalb White, rather than properties of bone, lower mean weight may imply higher levels of activity, higher risk of collisions, and lower soft tissue protection that reflect greater susceptibility to keel fracture.

龙骨骨折是蛋鸡行业面临的最大问题之一。在非笼式外壳中观察到最严重的影响，随着行业继续从电池笼过渡，频率有望急剧增加。商业系统内的事故已得到充分记录，据认为主要原因是产蛋量高以及相关的内源性储备（即骨）对钙的需求，使骨骼变弱并易于骨折。当前的工作试图表征5种不同的纯种或杂种蛋鸡品系的各种骨骼矿物质和生物力学特性（3种商业产品：Bovans Brown，Dekalb White和Institut deSélectionAnimale Dual Brown； 2种非商业用途：实验棕色和实验白色） ，之前的工作证明了使用离体撞击测试仪对龙骨断裂的敏感性不同。然后移走龙骨，以进行计算机断层扫描；肱骨和胫骨也被移除以进行生物力学测试。龙骨的矿物质密度和面积矩与母鸡体重和骨折易感性相关。胫骨（而不是肱骨）的生物力学特性与母鸡体重显示出很强的关系。一种具有高断裂敏感性的商业遗传品系（Dekalb White）表现出的平均胫骨强度低于其平均体重所预期的值。我们的结果表明，对于除Dekalb White以外的纯种或杂种系，而不是骨骼特性，较低的平均体重可能意味着较高的活动水平，较高的碰撞风险，