title: Non-linear increase of vitamin D content in eggs from chicks treated with increasing exposure times of ultraviolet light.
abstract: Vitamin D fortified food can help to reduce the prevalence for vitamin D deficiency. Previous data provided evidence that eggs from hens exposed to ultraviolet (UV) light contain large quantities of vitamin D. In the current study, we assessed the efficacy of vitamin D enrichment in eggs upon increasing daily UVB exposure times. We further addressed the question whether extended UVB irradiation affects the skin content of 7-dehydrocholesterol. To this end, 35 hens were assigned to 7 groups of 5 animals each and were exposed to UVB light (76μW/cm(2)) for 0, 15, 30, 60, 120, 180 and 300min per day, respectively. Eggs from the treatment groups were collected at baseline and after 2, 3 and 4 weeks of treatment, respectively. Skin samples were gained at the end of 4 weeks. Vitamin D metabolites were quantified by liquid chromatography-tandem mass spectrometry. The contents of vitamin D3 and 25(OH)D3 in egg yolk raised non-linear in response to increasing daily UVB exposure times. The vitamin D3 content did not reach a clear-cut plateau within the chosen UVB treatment times. A daily UVB exposure time of 300min resulted in vitamin D3 contents of 28.6μg/100g egg yolk dry matter. In contrast to vitamin D3, the 25(OH)D3 content in the egg yolk achieved a maximum upon an UVB irradiation time of 60min/d. The cutaneous 7-dehydrocholesterol contents were not altered in response to the chosen UVB irradiation times. In conclusion, the data show a distinct non-linear dose-response relationship of UVB exposure times on the total vitamin D content in eggs. This article is part of a special issue entitled '17th Vitamin D Workshop'.
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, Halle (Saale) 06120, Germany. Electronic address: julia.kuehn@landw.uni-halle.de.
authors.forename: Julia
authors.initials: J
authors.lastname: Kühn
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, Halle (Saale) 06120, Germany. Electronic address: alexandra.schutkowski@landw.uni-halle.de.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schutkowski
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, Halle (Saale) 06120, Germany. Electronic address: frank.hirche@landw.uni-halle.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Hirche
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, Halle (Saale) 06120, Germany. Electronic address: anja-christina.baur@student.uni-halle.de.
authors.forename: Anja C
authors.initials: AC
authors.lastname: Baur
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, Halle (Saale) 06120, Germany. Electronic address: norbert.mielenz@landw.uni-halle.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Mielenz
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, Halle (Saale) 06120, Germany. Electronic address: gabriele.stangl@landw.uni-halle.de.
authors.forename: Gabriele I
authors.initials: GI
authors.lastname: Stangl
mesh_terms: D000818:Animals; D002645:Chickens; D004531:Eggs / Q000032:analysis* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000378:metabolism*; D014815:Vitamins / Q000378:metabolism*
chemical_list: D014815:Vitamins; D014807:Vitamin D
keywords: Bio-addition; Egg; Laying hen; UVB; Vitamin D