Julia Kühn1, Alexandra Schutkowski1, Holger Kluge1, Frank Hirche1, Gabriele I Stangl2. 1. Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany. 2. Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany. Electronic address: Gabriele.stangl@landw.uni-halle.de.
Abstract
OBJECTIVE: Food-based strategies need to be developed to improve the vitamin D status of individuals. Recent studies identified ultraviolet B irradiation as an efficient method to enrich mushrooms and eggs with vitamin D. The aim of this study was to determine whether free-range farming of hens could provide a valuable method to produce vitamin D-enriched eggs. METHODS: Laying hens were randomly assigned to three groups of 33 to 34 animals each, and were kept either indoors (indoor group), outdoors (outdoor group), or with an indoor/outdoor option (indoor/outdoor group) over 4 wk. RESULTS: The study shows that the vitamin D3 content of egg yolk was three- to fourfold higher in the groups that were exposed to sunlight (outdoor and indoor/outdoor groups) compared with the indoor group (P < 0.001). Egg yolk from the outdoor group revealed the highest vitamin D3 content, which averaged 14.3 μg/100 g dry matter (DM), followed by that from the indoor/outdoor group (11.3 μg/100 g DM). Yolk from indoor eggs contained only 3.8 μg vitamin D/100 g DM. The 25-hydroxyvitamin D (25[OH]D3) content of egg yolk was also influenced by sunlight exposure, although less pronounced than the vitamin D content (P < 0.05). In contrast, free-range eggs randomly acquired from supermarkets had relatively low vitamin D contents. CONCLUSION: Free-range farming offers an efficient alternative to fortify eggs with vitamin D, provided that farming conditions are sufficiently attractive for hens to range outside.
OBJECTIVE: Food-based strategies need to be developed to improve the vitamin D status of individuals. Recent studies identified ultraviolet B irradiation as an efficient method to enrich mushrooms and eggs with vitamin D. The aim of this study was to determine whether free-range farming of hens could provide a valuable method to produce vitamin D-enriched eggs. METHODS: Laying hens were randomly assigned to three groups of 33 to 34 animals each, and were kept either indoors (indoor group), outdoors (outdoor group), or with an indoor/outdoor option (indoor/outdoor group) over 4 wk. RESULTS: The study shows that the vitamin D3 content of egg yolk was three- to fourfold higher in the groups that were exposed to sunlight (outdoor and indoor/outdoor groups) compared with the indoor group (P < 0.001). Egg yolk from the outdoor group revealed the highest vitamin D3 content, which averaged 14.3 μg/100 g dry matter (DM), followed by that from the indoor/outdoor group (11.3 μg/100 g DM). Yolk from indoor eggs contained only 3.8 μg vitamin D/100 g DM. The 25-hydroxyvitamin D (25[OH]D3) content of egg yolk was also influenced by sunlight exposure, although less pronounced than the vitamin D content (P < 0.05). In contrast, free-range eggs randomly acquired from supermarkets had relatively low vitamin D contents. CONCLUSION: Free-range farming offers an efficient alternative to fortify eggs with vitamin D, provided that farming conditions are sufficiently attractive for hens to range outside.
Authors: Janet Maxwell Roseland; Kristine Y Patterson; Karen W Andrews; Katherine M Phillips; Melissa M Phillips; Pamela R Pehrsson; Guy L Dufresne; Jette Jakobsen; Pavel A Gusev; Sushma Savarala; Quynhanh V Nguyen; Andrew J Makowski; Chad R Scheuerell; Guillaume P Larouche; Stephen A Wise; James M Harnly; Juhi R Williams; Joseph M Betz; Christine L Taylor Journal: J Agric Food Chem Date: 2016-04-15 Impact factor: 5.279