Deer are distinguished from other ruminant animals by the existence of antlers. Antlers are present in the male species of all deer, with the exception of Musk and Water deer. Caribou are the only deer species where females grow antlers also.
Antlers develop from two permanent stumps of bone referred to as Pedicles. These are situated on the skull directly between the ears. Antler growth takes about sixteen weeks, during this period the antlers are covered with a vascular, sensitive skin that is coated with hair. This skin is referred to as Velvet.
Inside the growing antler, as well as on the underside of the velvet there are numerous blood vessels supplying the blood that is required to promote antler growth. This is the reason that antlers have grooves and pearling. These grooves are where the blood flowed during antler growth. As a result the more pearled and grooved the antlers are, the more abundant the blood supply was.
When the antler is nearing growth completion, a ring of bone is formed (Coronet) at its base just above the junction with the pedicle. When antler growth is complete the ring or coronet will constrict thus reducing the blood flow. When this happens the velvet dries up and starts to peel off. What remains is white hard antler.
Once the antler is clean of all velvet it is no longer sensitive, but whilst the velvet is in the process of peeling, it would seem that there is some irritation for the deer and as a result the deer will continually seek foliage and trees to rub until all the velvet is removed. It is also at this time that antlers begin to absorb the sap from the foliage that will ultimately give them their final colour.
At this stage the deer will carry his antlers for a few months until there is an intensive calcification at the base of the main beam below the coronet. This shuts off the blood supply through the middle of the antler. This results in the antler becoming necrotic (dead), and also more brittle. As time goes by, an absorbent process between the now dead antler and the living tissue in the socket of the pedicle will cause the antler to fall off.
The loosening of the antler prior to casting would seem to be a very sudden process as separation of the antler from the pedicle may be caused by as little as a sudden movement of the deer’s head. There have also been instances when the proud hunter has lifted the head of a fallen stag only to have the antler separated from the head in his hands.
In the majority of cases antler growth and casting is repeated with great regularity each year at about the same time. A stag will retain his antlers for about eight months. However, there are occasions when a stag may cast early and also stags that may skip casting an entire year or more.
Not all stags will produce perfect antlers each year or even during their entire life. The reasons for these malformed antlers are numerous and cannot be determined in the field. From studies on various species of deer the two main factors that influence antler growth are genetics and nutrition. Injury to the deer can also affect antler growth.
Unlike most deer species in Australia, Sambar stags do not all cast their antlers during the same period. There will be stags in hard antler at anytime of the year, just as there will be stags that have cast or are in various stages of antler growth. Over the years our observations suggest that there seem to be more stags cast or in velvet during the summer months then during the winter.