Plasma concentrations of 25-hydroxycholecalciferol in 22 captive tortoises (Testudo species).

The plasma concentration of 25-hydroxycholecalciferol was measured in 13 adult Hermann's tortoises (Testudo hermanni), seven adult spur-thighed tortoises (Testudo graeca) and two adult marginated tortoises (Testudo marginata) during 2004. They were healthy, of both sexes, and kept in captivity under natural unfiltered sunlight in southern England with no dietary sources of cholecalciferol. Blood samples were taken in March, June and August, and the concentration of 25-hydroxycholecalciferol did not vary significantly with the seasons. However, the concentrations in the female tortoises were always significantly lower than in the males.