title: Effects of seasonal photoperiod on serum 25-hydroxycholecalciferol and calcium in reindeer, Rangifer tarandus tarandus.
abstract: In order to understand the effects of solar irradiance on calcium metabolism we measured serum 25-hydroxycholecalciferol and total calcium levels monthly in 6 female nonpregnant reindeer maintained in the Oulu area (65 degrees N). Mean monthly serum total calcium levels varied slightly and the highest levels were seen in October. Serum 25-hydroxycholecalciferol levels were highest in October but the monthly variation was also slight. The small monthly variation of the analytes' abundance and the fact that they peaked not until 4 months after the longest day, (i.e. the main stimulus for vitamin D synthesis) could have something to do with the supplementation of this vitamin in the diet of the captive reindeer.
authors.affiliation: Department of Physiology, University of Oulu, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Vierimaa
authors.forename: J
authors.initials: J
authors.lastname: Timisjärvi
authors.forename: E
authors.initials: E
authors.lastname: Eloranta
authors.forename: S
authors.initials: S
authors.lastname: Saarela
authors.forename: A
authors.initials: A
authors.lastname: Ruokonen
authors.forename: J
authors.initials: J
authors.lastname: Leppäluoto
mesh_terms: D000818:Animals; D002112:Calcifediol / Q000097:blood*; D002118:Calcium / Q000097:blood*; D005260:Female; D017440:Photoperiod; D012053:Reindeer / Q000502:physiology*; D012621:Seasons; D014466:Ultraviolet Rays
chemical_list: D002112:Calcifediol; D002118:Calcium