Effects of castration on antler growth in fallow deer (Dama dama L.)

Morphology and histological structure of antlers grown after castration (performed on March 25) were studied in six young fallow bucks. In the year after castration, antlerogenesis occurred during the species-specific time span, and the shape of the antlers, which remained permanently in velvet, was normal. During a cold period in December/January, the distal parts of the antlers suffered from frostbite and were subsequently detached. The process of sequestration was similar to that leading to normal antler casting. The sequestration sites were soon covered with skin, but (limited) regrowth of antler tissue from the stumps was not observed before late April/early May, i.e., the time of normal antler regeneration. Simultaneously, growth of knobby protuberances started on the surface of the antlers. Histological analysis of biopsies taken on December 20 in the year after castration revealed that the central parts of the antlers consisted of cancellous lamellar bone with mainly secondary osteons. Peripheral to this, the bone tissue (forming the protuberances) was of a more immature nature and exhibited larger intertrabecular spaces. The outermost layer consisted of woven bone formed by intramembranous ossification from the periosteum and was undergoing active growth and remodeling at the time of biopsy. Thus, bone formation at these sites occurred during a period when no antler growth is observed in normal fallow bucks. The velvet covering the bony protuberances was of normal appearance.