Vitamin D supplementation to improve laying hen robustness, longevity, and egg quality

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This partnership aims to improve the robustness of laying hens to better cope with nutritional, immune, and environmental stresses and thus improve their productivity and longevity in a context of lengthening of laying cycles. Indeed, successfully keeping the laying hens to 100 weeks is no longer the exception and there is a tendency for extending the laying hens cycle of commercial flocks to reach 500 eggs per cycle. The long-life laying hen are expecting helping saving costs in production, create additional value and profit, improve the welfare of the chicken, and reduce the environmental impact of egg production. However, the main reason to deplete a flock is not often related to the persistency in egg production, but because of eggshell quality that gradually goes down with age. Poor quality eggs, and especially weaker shells, can increase the costs of egg packing and customer complaints. This is probably the result of the osteoporosis that occurs with ageing that may lead to both welfare issues and financial losses. Recent results have showed an increase expression of Fibroblast Growth Factor 23 (FGF23) and a decreased plasma levels of 1.25(OH)2D3, the active form of vitamin D, with ageing (Gloux). Vitamin D is a well-known essential nutrient in laying hens which contributes to bone mineralization and mobilization by promoting the intestinal absorption of Ca and P and thus ensures good shell quality (Bar, 2008). Vitamin D could thus help extending the laying cycle while reducing the potential negative impact for the hen. Beyond the interest of vitamin D for the health of laying hens, studies have shown the possibility of biofortification in vitamin D in eggs for human health. The specific objectives of this partnership will be to test the addition of a vitamin D in a more active form up to 90 weeks of laying in terms on its prophylactic effect on phosphorus and calcium status, gut health, and immunity and overall performances.