Regulation of calcium metabolism in laying hens

In laying hens, calcium (Ca) is of great importance in the eggshell, which requires for synthesis the deposition of about 2.2 g of Ca in the form of Ca carbonate (CaCO3). As egg production will be repeated daily over a long period (50 to 80 weeks), the hen finally exports huge amounts of body Ca for this purpose. Moreover, as the eggshell synthesis occurs mainly during the dark period, when the digestive tract is empty, an additional Ca reserve is mobilized from its bone with a very rapid bone turnover representing a huge challenge to Ca homeostasis and its underlying regulations. The available knowledge on the subject is presented and discussed in the following manuscript, with reference to applied perspectives for the egg producing sector.