Antler Growth in Red Deer Stags Implanted with an Antiandrogen

Abstract

The red deer is a species with a seasonal antler cycle. The development and mineralization of antlers is closely related to the sexual cycle. Variations in levels of sexual hormones play a major role in the timing of individual phases of antler growth. Testosterone (T) appears to be the hormone which most directly affects the antler cycle. The casting of antlers in cervid species in temperate regions is generally believed to be caused by a sudden drop in T levels. It has been already suggested, however, that this fits only to one group of species such as white-tailed deer (Odocoileus virginianus), mule-deer (0. hemionus), moose (Alces), reindeer, and caribou (Rangifer), where an interval exists between antler casting and new antler growth. Species where casting of old antlers is followed immediately by the growth of new antlers, such as wapiti (Cervus canadensis), red (C. elaphus), roe (Capreolus), fallow (Dama dama), Pere David’s (Elaphurus davidianus) and sika deer (C.e. nippon), may cast their antlers after a short-termed restoration of T levels following the seasonal T drop. Twelve male red deer were used. Before the antler casting the deer were either implanted with cyproterone acetate in silastic tubes or sham-implanted. In the present study we take into consideration the following factors: the time of the antiandrogen application before antler casting; antler casting, growth, and cleaning; and hair moulting.