Antler Growth

From Fay Rowantree at Wild Highland Tours:

What is horn and what is antler?

Antlers differ from horns in that they are shed and reproduced annually. Antlers are made of bone while horns are made of keratin, the same material as your fingernails. Horns are a thin sheath grown over a portion of the skull while antlers are completely separate to the skull, held on only by a small section nourished by vitamins and minerals with the ability to start and stop growth. Horns grow continuously while antlers grow for around 128 days. Antlers are the fastest growing tissue in the animal kingdom growing at up to 2.5 cms per day and can be grown only by Cervidae. Horns are grown by cattle, goats, sheep and antelope.

How an antler grows

Antlerogenesis is the term that describes the annual physiological production of antlers. It is regulated by a series of interconnected processes. Antler growth is primarily regulated by testosterone levels. The testosterone levels in a stag’s body are regulated by photo-period, or length of daylight, and length of daylight is regulated by the seasons that occur from the tilting and rotation of the Earth. Because of all of this, the antler growing process lasts only 128 days and cannot be extended or expanded.

When first born in the spring time, a stag calf or buck fawn has small indentions and hair swirls on the frontal bone of his skull. Before being a year old the buck or stag is affected by increased testosterone levels which help to produce small, flat platforms called pedicles. Pedicles provide the structural base for the foundation of future antler development in all male deer. At approximately ten months of age and in good conditions, the young male’s testosterone level increases enough to produce his first set of antlers. By the next autumn, the young stags will be about eighteen months of age and referred to by deer managers as “knobbers”.  Under ideal conditions and with good genetics, his first antlers can have more than two points but most only have two spikes. 

As antler growth begins, the underlying pedicle gives rise to new antler material, which at this point is a semi-firm tissue composed of approximately 80% protein. This growing material is cartilage-like and full of blood vessels. The nutrient-rich transporting blood vessels rise up through the pedicle as well as form the soft lining around the outside of the growing antler. The tiny little blood vessels and protective hairs are what we refer to as velvet when a buck or stag is actively growing antlers. Blood vessel density and capacity is what “feeds” the growing antlers. A healthy male produces and maintains a high volume of blood vessels and draws heavily on nutrients during this period. The velvet is also full of a dense network of microscopic nerves. The nerves make the velvet covered antlers sensitive and help to protect the soft growing tissue against damage. The nerves may also make the stag aware of how his antlers are shaped, which will be useful when stripping the velvet and sparring with competing stags. The visible grooves on the base and beams of hardened antlers are the impressions left by the blood vessels as it grew in velvet. The scab that forms over the wound left by the cast antler heals and becomes covered with fine, thin hairs. The fine-haired skin forms the beginnings that will nourish and protect the growing antlers for the next four months.

Many thanks to Fay for the article and top photo.

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