Plasma calcemic hormones in mature female reindeer, Rangifer tarandus.

The plasma calcemic hormones in mature female reindeer were measured during the major portion of the antler growth cycle, between the months of March and November. Blood samples were collected every 2 months, a total of five samples each from eight reindeer. Plasma levels of 25-hydroxyvitamin D, PTH, and osteocalcin were found to increase progressively from May through July and decline thereafter except 1,25-dihydroxyvitamin D level which peaked in September. No change in plasma total Ca was observed at any time of the year. Plasma estradiol level was elevated in March only. All animals grew and shed antlers between April and February. This suggests that during the antler growth period when the deer undergoes cyclic bone loss, corresponding changes in plasma calcemic hormones occur, which may account for the reported skeletal bone changes seen during the growth of the antler.