EFFECTS OF AN ANTIANDROGEN TREATMENT ON THE ANTLER CYCLE OF MALE FALLOW DEER (DAMA-DAMA L)

Weekly application of the antiandrogen cyproteron acetate (CA) to 3 ad ult (group 1, treatment starting 3 weeks prior to the rut) and 4 subad ult (group 2, treatment starting after the rut) fallow bucks led to pr emature antler casting after about 9 weeks (group 1) or 16 to 17 days (group 2). Variation in time span between onset of CA administration a nd induced casting (in late November/early December) is attributed to age- and season-dependent differences in androgen levels before and du ring the treatment period. Casting surfaces of the antlers were flat. In all bucks, casting was followed by a complete though shortened antl er cycle, occurring under short day conditions. In February/March velv et was shed from the antlers, indicating a rise in plasma androgen lev els at that time. At time of fraying, antlers exhibited signs of immat urity and were shorter than normal. In the most pronounced case of imm aturity, the antlers consisted mainly of cancellous woven bone, reveal ing that bone remodeling and antler mineralization had not occurred to a larger extent. These observations prove that onset of fraying behav iour does not depend on prior maturation of antler bone or necrosis of velvet. Occurrence of the additional antler cycle in late autumn and winter had no negative effect on subsequent antler formation starting in the following spring.