ABSTRACT

1. Bone tissue adapts continuously to metabolic calcium demands, as well as to external forces due to physical weight loading subject to hen movement. Limited calcium metabolism and, subsequently, its availability from the medullary bone, is a major factor contributing to reduced eggshell quality in hens in the late laying period (>60 weeks of age).

2. Increasing physical activity and biomechanical loading during hen rearing has been demonstrated to increase skeletal strength, enhancing bone mass as well as endocortical and periosteal bone metabolism. Presently, the consequences of range use during lay on bone quality characteristics in laying hens remain unknown.

3.The aims of this study were to characterise tibiotarsal bone indices and evaluate the impact of range access during lay on tibia bone quality in commercial free-range laying hens.

4. This exploratory study described and analysed the volumetric measurements, morphological mechanical and trabeculae indices of the tibiotarsal bone of 48 Lohmann Brown laying hens at 74 weeks of age. All bone parameters were obtained using micro-computed tomography and correlated with individual hen range use.

5. Range usage throughout lay was not associated with tibial trabecular architecture (bone volume and fraction, trabecular thickness, trabecular connectivity density and structural model index), or any other morphological characteristics (breaking strength, diaphyseal diameter, bone weight and bone mineral density) of the tibia (P > 0.05) when hens were 74 weeks of age.

6. The results demonstrated a large variation in individual bone characteristics and suggested that range usage was not associated with bone quality in commercial free-range laying hens used in this study. In conclusion, the bone health of free-range commercial laying hens may be positively impacted by other features, such as hen genetics, feed, the quality of pullet rearing, perch availability or other shed equipment, and the benefits of these variables exceed the benefit of range use.

摘要

1.骨骼组织持续适应新陈代谢的钙需求，以及由于母鸡运动引起的身体重量负荷而产生的外力。有限的钙代谢以及随后从髓质中获得钙，是导致产蛋后期（> 60周龄）蛋壳质量下降的主要因素。

2.已经证明，在母鸡饲养过程中增加体育锻炼和生物力学负荷可以增加骨骼强度，增加骨量以及皮质和骨膜和骨膜的骨代谢。目前，蛋鸡在产蛋期间使用范围对骨质特性的影响仍然未知。

3这项研究的目的是表征胫骨s骨指数，并评估产蛋散养母鸡产蛋过程中进出对胫骨质量的影响。

4.这项探索性研究描述并分析了74周龄48头Lohmann Brown蛋鸡的胫骨s骨的体积测量，形态力学和骨小梁指数。所有骨参数均使用微计算机断层扫描获得，并与个体母鸡使用范围相关。

5.整个产程的范围使用与胫骨小梁结构（骨体积和分数，小梁厚度，小梁连接密度和结构模型指数）或任何其他形态特征（断裂强度，骨干直径，骨重和骨矿物质密度）无关母鸡74周龄时的胫骨缺损（P> 0.05）。

6.结果表明，本研究中使用的商业散养蛋鸡的个体骨骼特征差异很大，并表明范围的使用与骨骼质量无关。总之，散养商业蛋鸡的骨骼健康可能会受到其他特征的积极影响，例如母鸡遗传，饲料，母鸡饲养质量，鲈鱼可利用性或其他棚设备，并且这些变量的好处超过了好处使用范围。