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

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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).****