ANIHWA call 2: Better bone quality in laying hens

蛋鸡可以在一年多的时间里经济地产蛋；这是一种高度可消化的蛋白质，对改善世界营养状况做出了很大贡献。然而，长时间的鸡蛋生产可能会伴随着相关的骨骼病理问题。在产卵过程中，雌激素会在长骨的腔内诱导髓质骨的形成，这是一种钙存储形式。这种骨骼高度不稳定，在贝壳形成过程中迅速翻转。成骨细胞在蛋鸡的髓质骨形成过程中几乎是唯一活跃的；然而，破骨细胞也作用于结构性皮质骨，破骨细胞重新吸收髓质骨以将钙运输到壳腺。这会导致骨骼变弱(骨质疏松症)，并容易骨折。非椎间融合器系统会增加骨折和龙骨畸形(&gt；50%)，从而加剧这一问题。随着对经济型食物的需求不太可能减少，需要改善骨骼健康的解决方案。我们已经证明，在商业纯种系中存在遗传潜力，既可以产下大量的鸡蛋，又可以具有良好的骨骼质量。然而，骨骼质量的评估方法依赖于杀死鸟类，这排除了后续的繁殖。为了应对这一问题，我们已经开发了许多方法来发现遗传标记，我们已经确定了一种代谢标记，可以解释骨骼质量的差异。我们的目标是验证这些标记，并开发一种新的不需要宰杀母鸡的骨骼质量表型测量方法。该项目将建立在最近完成或正在进行的研究的基础上，以检测预测骨骼质量的遗传标记，这些标记仅限于一种母鸡。这项研究将使用准静态强度测量、密度测量以及分析技术(红外光谱、二维X射线衍射)来研究骨的化学和结构，以全面了解定义骨表型的因素。这些种群将来自两种类型的母鸡，将被用于验证标记是否用于选择。这些群体还将被用于验证新的表型工具(定量轴向超声)，并用于我们已经证明与骨密度相关的血液代谢物的测量。通过使用一系列方法，我们希望向育种者提供实用的解决方案，使骨骼更好的蛋鸡的遗传潜力得以实现。

Laying hens can produce eggs economically for over a year; a highly digestible protein that has done much to improve world nutrition. However the long period of egg production can come with correlated problems of bone pathology. During egg laying oestrogen induces the formation of medullary bone, a form of calcium storage, in the cavities of the long bones. This bone is highly labile and turns over rapidly during shell formation. The bone forming osteoblasts are almost exclusively active during the formation of medullary bone during lay; however the osteoclasts, which reabsorb the medullary bone for calcium transport to the shell gland, act also on the structural cortical bone. This results in weaker bones (osteoporosis) and susceptibility to bone fracture. Non-cage systems exacerbate the problem with increases in bone fracture and keel bone deformities (>50%). With the demand for economical food unlikely to reduce, solutions to improve bone health are required.We have shown that there is the genetic potential within commercial pure lines to both lay a high number of eggs and have good bone quality. However the method of assessment of bone quality relies on killing the birds, which precludes subsequent breeding. To counter this, we have developed a number of approaches to discover genetic markers and we have identified a metabolic marker which explains variance in bone quality. Our aim will be to validate these markers and develop a novel phenotypic measurement for bone quality which does not require killing the hen.The project will build on studies recently completed or under way to detect genetic markers which predict bone quality which have been confined to one line of hens. The study will use quasi static strength measurement, density measurement as well as analytical techniques (infrared spectrometry, 2D X-ray diffraction) to study the chemistry and structure of bone to give a comprehensive insight in to factors defining bone phenotype. These populations, which will be from two types of hen, will be used to validate the markers for use in selection. The populations will also be used to validate the new phenotypic tool (quantitative axial ultrasound) and for the measurement of the blood metabolite which we have shown to be correlated to bone density. By using an array of approaches we expect to deliver practical solutions to breeders that will allow the genetic potential of laying hens with better bone to be realised.