Photoperiod disruption of physiological activity of gonadotrophs in the anterior pituitary gland and its effects on antlerogenesis in captive cervids held in polar regions.
Jim Heffelfinger, Arizona Game and Fish Department, 555 N. Greasewood, Tucson, AZ

ABSTRACT Past research has shown that artificially induced variations in photoperiod can cause changes in adenohypophyseal acidophil cell morphophysiology resulting in an irregular timing of antlerogenesis in some male cervids. Casual observation of a small herd of captive cervids held in a polar region has revealed alarming antler cycle irregularities. Domesticated reindeer (Rangifer tarandus) from a captive herd at the North Pole were observed on the evening of 24 December in each of 10 years, 2000-2009. All 8 individuals were consistently observed in full velvet.

These abnormal antler cycles and inhibition of secondary ossification may be caused by insufficient vascular testosterone levels resulting from an endocrine system which is maladapted to that polar region. The acidophil cell cytoplasmic area in these individuals is apparently responding to photoperiod cycles which are different than those with which they evolved. This maladaption results in the animals retaining their velvet well into January. This abnormality may have significance from a survival standpoint since the highly vascularized antlers would result in an undetermined but certainly detrimental amount of heat loss.

Another abnormality which has been reported in this herd is the occurrence of a young male with a rhinarium distinctively colored red (some even say it glows). It is unclear if this abnormality is a mutation causing an unnatural pigmentation, but it apparently affected the individual’s social interactions with other members of the herd. This may also be related to diet as the owner is reported to feed some sort of “special corn.”

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