Improving bone health and eggshell quality through maintaining a desired calcium homeostasis in laying hens

蛋鸡有一个动态的骨转换与每天的产蛋周期有关。由于快速的骨转换和钙从骨骼中动员蛋壳形成，结构骨的进行性损失（骨质疏松症）是蛋鸡行业的一个大问题。骨质疏松症是老年蛋鸡骨折的主要原因之一，这与疼痛、产蛋、蛋壳质量和动物福利问题有关。因此，有必要进一步研究蛋鸡的骨代谢，从而制定遗传、营养和/或管理策略，以保持高效生产，提高动物福利、骨骼健康和蛋壳质量。本试验旨在研究饲粮中添加有效量的家禽钙敏感受体（CaSR）调节剂、钙源和25-羟基胆钙化醇对蛋鸡钙稳态、蛋壳品质和骨密度的影响。我们将首先研究蛋鸡壳腺和骨中家禽CaSR的表达，然后在体外鉴定家禽CaSR的潜在调节剂。我们还将研究CaSR调节剂和25-羟基胆骨化醇如何调节成骨细胞和间充质干细胞的分化。最后，我们将在体内研究CaSR调节剂、钙源和25-羟基胆酸醇对骨骼健康和蛋壳质量的影响。这些结果将有助于我们了解蛋壳腺和骨骼钙稳态的分子机制，并为改善蛋鸡骨骼健康和蛋壳质量提供营养途径。该项目有两个行业合作伙伴，包括马尼托巴蛋农（MEF）和华伦斯坦饲料供应有限公司（WFS）。

Laying hens have a dynamic bone turnover associated with a daily egg laying cycle. Because of rapid bone turnover and calcium mobilization from bones for eggshell formation, progressive loss of structural bone (osteoporosis) is a big concern in the laying hen industry. Osteoporosis is one of the major causes for bone fractures in older laying hens, which are associated with pain, egg production, eggshell quality and animal welfare issues. Therefore, there is a need for future research to understand bone metabolism in laying hens and then develop genetic, nutritional and /or management strategies to maintain efficient production and improve animal welfare, bone health and eggshell quality. This proposal is to investigate the effects of administering an effective amount of poultry calcium sensing receptor (CaSR) modulators, calcium sources, and 25-hydroxycholecalciferol on calcium homeostasis, eggshell quality and bone density in laying hens. We will first investigate the expression of poultry CaSR in shell gland and bone in laying hens and then identify the potential modulators of poultry CaSR in vitro. We will also examine how CaSR modulators and 25-hydroxycholecalciferol regulates the differentiation of osteoblast and mesenchymal stem cells. Finally, we will investigate the effects of CaSR modulators, calcium sources and 25-hydroxycholecaciferol on bone health and eggshell quality in vivo. These results will help us to understand the molecular mechanisms of calcium homeostasis in shell gland and bone, and to develop nutritional approaches to improve bone health and eggshell quality in laying hens. There are two industry partners in this project including Manitoba Egg Farmers (MEF) and Wallenstein Feed & Supply Ltd. (WFS).