ANTLER HARVEST

   Restraint Methods

   Correct Anesthesia

ANTLER COMPOSITION AND QUALITY

VELVET ANTLER HARVEST

It has been said that “there is no place for antlers on a deer farm”. Bucks carrying hard antler in confinement can be dangerous to each other and to handlers, and of course the onset of rut and the breeding season exacerbates the problems. Animals in soft antler are prone to injury during handling and transport. Besides, the antler at this stage may be a valuable commodity after removal from the animal. In animals whose antlers are not commercially useful the antler can be removed after hardening when the nerve and blood supply have regressed, but for easier management and for behavioral reasons, it is simpler and safer to remove antlers during the velvet stage.

The traditional Chinese method for removal of velvet antler involved the physical restraint of the animal and separation of the antler from the deer as rapidly as possible without any analgesia (pain prevention). It was felt that the more excited the deer, the better the quality of antler because an increase in blood pressure is thought to increase the blood content of the harvested antler. These methods are no longer considered acceptable by most agricultural communities in the world. The harvesting of velvet antler is illegal in Great Britain, California, and a number of European and Scandinavian countries. Under certain conditions, it is permitted in Canada, most states of the USA, New Zealand, Australia and most other countries which are currently farming deer. If the velvet antler industry wishes to establish its product in the rapidly developing “western” market for non-traditional medical products, it must be seen to be protecting the welfare of the animals on which it depends. This means harvesting antler under conditions that are proven humane and safe for the animal. Harvesting soft antler without analgesia is irresponsible and inhumane.

There are three currently accepted methods of preparing a deer for antler removal. The animal is physically restrained in one of several types of restraint chute, or it is given drugs to induce general anesthesia. The third method is a combination of physical and chemical restraint where drugs are used to allow easier handling of the animal.

Any method other than general anesthesia should include local anesthesia of the antler. The generally accepted means of local anesthesia in an awake animal is the infiltration of lidocaine solution around the base of the pedicle, effectively “freezing” the nerves serving the antler. In the recent past, an alternate method using “electroanesthesia” of the antler was used by some producers. This technique involves physical restraint in a squeeze chute followed by the placing of electrodes on the head such that a low voltage, high frequency current passes over the pedicles. Electroanesthesia  is not an approved method in any deer farming country, and has been scientifically shown to be ineffective at providing local anesthesia. A newer non-chemical means of antler analgesia using compression of the antler pedicle is currently under investigation in the elk industry.

Local injectable anesthesia of the antler is achieved through the placement of lidocaine at strategic points on the head of the animal in order to block the nerve supply to the antler. A ring block is performed at the base of the pedicle. The local anesthetic is infiltrated by multiple subcutaneous injections that encircle the pedicle. Effective anesthesia is attained within 3 or 4 minutes.

Once correct restraint and anesthesia have been achieved, a tourniquet is applied to the base of each pedicle and a suitable saw is used to remove the antler at a point approximately 2.5 cm above the coronet, or antler pedicle junction. The cut surface of the remaining antler is sometimes dressed with antibiotic/hemostatic powder and the tourniquet removed after an appropriate length of time but some bleeding is enevitable. The remaining stump of antler will harden and fall off according to the regular cycle of events in antler growth. 

Antler Composition and Quality

The composition of hard antler is similar to bone. It contains approx. 25% calcium and 19% phosphorous by weight. Organic matter makes up about 39% of the antler by weight, and water content is 8%.

As one might expect, the composition of velvet antler depends on the stage of growth. Growing antler contains a complex variety of hormones, growth factors, minerals and compounds. To complicate things further, the relative amounts of the constituents also vary according to what part of the antler is analyzed. For example, the selenium levels in the growing tip of the antler are 5 to 10 times that which are found elsewhere in the antler.

In general, those portions closer to the tip of the antler have a higher relative content of lipid (fatty acid) fraction. Those portions farther from the tip have higher ash (mineral) content. The converse relationships are also true. In general, as the antler matures and the antler weight increases, the relative amount of ash increases and the relative amount of lipid decreases. The relative content of calcium and phosphorous increases over time and the relative amounts of selenium, sodium, potassium, and sulphur decrease.

New Zealand research into the characteristics of antler quality have led to the identification of several compounds as being indicators of biological activity and therefore quality. Two of them are phosholipids, and free amino acids. Gangliosides are animal phospholipids occurring mainly in the central nervous system but also distributed in other tissues. They  are believed to be biologically active and therefore important for antler quality. Free amino acids (FAA) are the basic building blocks from which proteins are made. They are essential nutrients for cell growth and because they are found in high concentrations in rapidly growing tissue, are in abundance in velvet antler. A number of amino acids are “essential” amino acids in the sense that they cannot be synthesized from other dietary material in the diet and must be provided as is for optimal growth of animals. Velvet antler, as a dietary supplement, might be expected to provide high levels of essential amino acids.

There are many biologically active compounds in antler. There are growth factors such as bone growth factor, nerve growth factor, and epithelial growth factor. The anti-arthritic properties of velvet antler are thought to be due to the glcosaminoglycans and chondroitin sulfate content of antler cartilage.

Studies have shown that there is a significant decrease in the concentrations of bioactive compound content from the tip of the antler to the base. Most of the value of the harvested soft antler is therefore in the growing end of the antler.

New Zealand research has also examined the biological effectiveness of various antler extracts. Researchers have developed both aqueous and organic extractions of velvet antler, and not surprisingly have shown that the yield of extractable substances is higher in the tips compared with the bases.

Organic (fat soluble) extracts from antlers have been tested in an antitumour assay. Samples of extract were incubated with mouse leukemia cells. There was a significant reduction in leukemia cell growth that was dependent on the concentration of the antler extract used in the experiment..

The aqueous (water soluble) extracts have been evaluated for biological effectiveness by measuring their effects on the growth of antler cells in tissue culture. The results show that there are potent stimulators of cell division in antler extracts. It was also shown that there is considerable variation in the ability of the extract to stimulate cell division and growth from antler to antler and also the portion of antler sampled.

In the future, determination of antler quality and economic value, will possibly place more reliance on the content of the antler expressed in terms of biologically active substances than on the traditional assessment of weight, size, shape and color. White-tailed and mule deer antler contain all of the compounds and minerals that antler from other species contains, but at current market price the small size of the velvet antler means that velvet harvesting in these species is not profitable.

Antler removal in white-tailed and mule deer is still a good idea. Unless the buck is to be harvested in the fall, or a full antlered animal is needed for marketing, antlers should be removed before they become a problem in the rut. Year after year we hear stories about producers who have been ventilated, some of them fatally, by a buck. It is usually an animal that has become accustomed to, and has lost its fear of humans. Breeding bucks sometimes injure does during the rut and younger bucks can cause damage to each other when rearranging the peck order in the herd. Semen sampling and drawing is best performed using non-antlered bucks for human and buck safety. As herds grow, deer producers will be cutting greater numbers of antlers at an early stage out of necessity and convenience.  

Bibliography

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Murray R. Woodbury DVM, MSc

Large Animal Clinical Sciences

Western College of Veterinary Medicine

Saskatoon, Canada