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Plasma 25-hydroxyvitamin D3 concentrations in Hermann's tortoises (Testudo hermanni) exposed to natural sunlight and two artificial ultraviolet radiation sources

Paolo Selleri DMV, PhD1 and Nicola Di Girolamo DMV2
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  • 1 Clinica per Animali Esotici, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51–53, 00137 Rome, Italy.
  • | 2 Clinica per Animali Esotici, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51–53, 00137 Rome, Italy.

Abstract

Objective—To determine the effect of various UVB radiation sources on plasma 25-hydroxyvitamin D3 concentrations in Hermann's tortoises (Testudo hermanni).

Animals—18 healthy Hermann's tortoises.

Procedures—Tortoises were exposed to sunlight in an outdoor enclosure located in the natural geographic range of Hermann's tortoises (n = 6 tortoises) or a self-ballasted mercury-vapor lamp (6) or fluorescent UVB-emitting lamp (6) in an indoor enclosure for 35 days. Plasma samples were obtained from each tortoise on the first (day 0) and last (day 35) days of the study, and concentrations of 25-hydroxyvitamin D3 were determined. Amount of UVB radiation in enclosures was measured.

Results—Mean ± SD plasma 25-hydroxyvitamin D3 concentrations for tortoises exposed to the mercury-vapor and fluorescent lamps were significantly lower on day 35 (155.69 ± 80.71 nmol/L and 134.42 ± 51.42 nmol/L, respectively) than they were on day 0 (368.02 ± 119.34 nmol/L and 313.69 ± 109.54 nmol/L, respectively). Mean ± SD plasma 25-hydroxyvitamin D3 concentration for tortoises exposed to sunlight did not differ significantly between days 0 (387.74 ± 114.56 nmol/L) and 35 (411.51 ± 189.75 nmol/L). Mean day 35 plasma 25-hydroxyvitamin D3 concentration was significantly higher for tortoises exposed to sunlight versus those exposed to mercury-vapor or fluorescent lamps. Sunlight provided significantly more UVB radiation than did the mercury-vapor or fluorescent lamps.

Conclusions and Clinical Relevance—Plasma 25-hydroxyvitamin D3 concentrations differed between tortoises exposed to sunlight and those exposed to artificial UVB sources. Exposure to sunlight at a latitude similar to that of the natural geographic range is recommended for healthy and calcium-deficient tortoises.

Abstract

Objective—To determine the effect of various UVB radiation sources on plasma 25-hydroxyvitamin D3 concentrations in Hermann's tortoises (Testudo hermanni).

Animals—18 healthy Hermann's tortoises.

Procedures—Tortoises were exposed to sunlight in an outdoor enclosure located in the natural geographic range of Hermann's tortoises (n = 6 tortoises) or a self-ballasted mercury-vapor lamp (6) or fluorescent UVB-emitting lamp (6) in an indoor enclosure for 35 days. Plasma samples were obtained from each tortoise on the first (day 0) and last (day 35) days of the study, and concentrations of 25-hydroxyvitamin D3 were determined. Amount of UVB radiation in enclosures was measured.

Results—Mean ± SD plasma 25-hydroxyvitamin D3 concentrations for tortoises exposed to the mercury-vapor and fluorescent lamps were significantly lower on day 35 (155.69 ± 80.71 nmol/L and 134.42 ± 51.42 nmol/L, respectively) than they were on day 0 (368.02 ± 119.34 nmol/L and 313.69 ± 109.54 nmol/L, respectively). Mean ± SD plasma 25-hydroxyvitamin D3 concentration for tortoises exposed to sunlight did not differ significantly between days 0 (387.74 ± 114.56 nmol/L) and 35 (411.51 ± 189.75 nmol/L). Mean day 35 plasma 25-hydroxyvitamin D3 concentration was significantly higher for tortoises exposed to sunlight versus those exposed to mercury-vapor or fluorescent lamps. Sunlight provided significantly more UVB radiation than did the mercury-vapor or fluorescent lamps.

Conclusions and Clinical Relevance—Plasma 25-hydroxyvitamin D3 concentrations differed between tortoises exposed to sunlight and those exposed to artificial UVB sources. Exposure to sunlight at a latitude similar to that of the natural geographic range is recommended for healthy and calcium-deficient tortoises.

Contributor Notes

Presented in abstract form at the 18th Annual Conference of the Association of Reptilian and Amphibian Veterinarians, Seattle, August 2011.

The authors thank Professor Gloria Isani and Dr. Annunziata Cannavacciuolo for assistance with performance of assays, Dr. Raffaele Melidone and Dr. Alessandro Di Girolamo for assistance with study design, and Dr. Elena Marini, Eleonora Malerba, and Lorenzo Gaspari for technical assistance.

Address correspondence to Dr. Di Girolamo (nicoladiggi@gmail.com).