title: Effects of vitamin D3 supplementation and UVb exposure on the growth and plasma concentration of vitamin D3 metabolites in juvenile bearded dragons (Pogona vitticeps).
abstract: The effectiveness of dietary vitamin D3 and UVb exposure on plasma vitamin D metabolites in growing bearded dragons (Pogona vitticeps) was studied. A total of 84 (40 males and 44 females) newly hatched bearded dragons were allocated to six levels of oral vitamin D3 supplementation (0 to 400%) or six UVb exposure times (2 to 12 h). At 3 and 6 months of age, blood samples were obtained from each animal and analysed for 25(OH)D3 and 1,25(OH)2D3. At 3 months of age, plasma concentrations of 25(OH)D3 did not increase with increasing vitamin D3 supplementation unlike the 1,25(OH)2D3. At 6 months of age, plasma concentrations of both 25(OH)D(3) and 1,25(OH)2D3 increased with increasing vitamin D(3) supplementation. Plasma concentrations in UVb-exposed animals were 18 times higher for 25(OH)D3 (178.4+/-9.0 vs. 9.9+/-1.3 nmol/L) and 5.3 times higher for 1,25(OH)2D3 (1.205+/-0.100 vs. 0.229+/-0.025 nmol/L) than in vitamin D(3) supplemented animals at 6 months of age. This study shows that 2h of UVb exposure enables adequate physiological concentrations of plasma vitamin D metabolites to be maintained in growing bearded dragons. Oral supplementation of vitamin D(3) is ineffective in raising plasma concentrations of 25(OH)D3 and 1,25(OH)2D3 to concentrations observed in UVb-exposed animals.
authors.affiliation: Animal Nutrition Group, Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands.
authors.forename: D G A B
authors.initials: DG
authors.lastname: Oonincx
authors.forename: Y
authors.initials: Y
authors.lastname: Stevens
authors.forename: J J G C
authors.initials: JJ
authors.lastname: van den Borne
authors.forename: J P T M
authors.initials: JP
authors.lastname: van Leeuwen
authors.forename: W H
authors.initials: WH
authors.lastname: Hendriks
mesh_terms: D000818:Animals; D002112:Calcifediol / Q000097:blood*; D002117:Calcitriol / Q000097:blood*; D002762:Cholecalciferol / Q000008:administration & dosage / Q000494:pharmacology*; D019587:Dietary Supplements; D005260:Female; D008116:Lizards / Q000097:blood* / Q000254:growth & development; D008297:Male; D014466:Ultraviolet Rays; D014815:Vitamins / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014815:Vitamins; D002762:Cholecalciferol; D002117:Calcitriol; D002112:Calcifediol