It's All About the Rack, by Dr. Mike Messman
Antlers on deer are pretty interesting phenomena, and have been fascinating people for ages. The annual cycle of growing, carrying, shedding and growing antlers again is more complicated than it looks, and takes more than a weekend in the woods to come by a respectable pair…at least it does if you’re a whitetail buck.
The antler growing cycle is process that lasts about 10-months. It starts in March or April with pedicle development and ending in January or February when antlers are shed. The months of the year can be slightly different depending if you live in the South or the North. In the whitetail deer this process is driven by photo period. When the days start to lengthen, the pineal gland in the brain notices the change and signals the pituitary to produce more of the hormone testosterone. Testicle circumference is increased serum testosterone increases, and more mature bucks will start to “muscle up”. Testicular circumference and testosterone levels peak at the height of the rut and decrease rapidly into January. This drop in testosterone is why bucks shed their antlers. Muscle tone will also decrease and bucks will deposit more fat as an energy store for winter.
Antler growth takes place in the tips of the antlers. As antlers grow, blood is circulated up through the pedicle, through the antler and to the tips. The growing antler is a soft cartilage type tissue that is very delicate. Antlers are covered by velvet during growth, which contains many blood vessels and nerve endings. This network of blood vessels and nerves is necessary to transport the nutrients to the rapidly growing antler. In general, during April to June the brow-tine and fork of the antler become apparent if the buck will be more than a spike. Antler growth really takes off in July when antlers can grow a ½ inch or more per day. During the antler growth period when the antlers are encased in velvet, antlers are 20% dry matter, 80%crude protein, 22%calcium and 11%phosphorus. By the end of July all points can probably be seen but some tine elongation may still take place in August. In September bucks will shed the velvet and polish their antlers. Mature polished antlers are 60%dry matter, 40%crude protein, 25 to 35%calcium and 19%phosphorus. Mature polished antlers will remain in the beginning of October. Into December thru February bucks will shed antlers and the process will start over again.
Three major factors that determine antler size are: age of the buck, genetics of the animal, and nutrition. Said another way, a buck will not reach maximum antler size unless he has the genetics, is a healthy mature buck greater than five years old and has consumed the nutrients needed to achieve his genetic potential. Hunters and landowners have some control over these factors as they manage hunting areas. Here’s how:
- First and most importantly, avoid harvesting young bucks. Take only the bucks that are at least five years old. This doesn’t come easily, but it’s one way to manage for bucks with optimum antlers. Granted, it's much easier on a large plot of land but small landowners can work together to manage an area of a few hundred acres and make a difference. Keep in mind that if the deer herd has the proper age structure and buck to doe ratio, bucks that exhibit less than desirable antler characteristics can be removed at an earlier age (3-4 years old). Research has shown that this age class of deer does the majority of the breeding during the rut. Remember, this should only be practiced when your herd has the proper age structure with at least 30%of your bucks being in the 5.5 or older age bracket.
- Having said that, the second factor is genetics: Harvest the mature bucks displaying undesirable antler characteristics to make sure you have the best possible gene pool.
- Third and finally, provide as near to optimum nutrition for the deer as possible. Antler growth from pedicle development to velvet shedding takes about 100 days on average, but feeding for antler growth is a 365-day a year job. In March and April, as pedicle development starts, the buck needs amino acids from protein and minerals. These can come from the diet the buck is consuming. During antler growth from pedicle to the forked antler stage the buck pulls amino acids from the diet consumed, but minerals start to come from bone reserves. During the rapid growth phase of antler development, late June through mid August the buck can’t consume enough amino acids or minerals to meet the maximum possible antler growth rate so the buck has to pull from bone and body reserves to do this. If there aren’t ample reserves to pull from, you can forget maximum antler production. Poor reserves mean that the main beam could have a smaller diameter, points could be reduced in size, or number of points off the main beam could be reduced. By the end of August or September when antler growth is done and velvet is shed, antler growth— and hence nutrient demand for their growth—is also done.
Although this year’s set of antlers are what they are, in the fall the buck starts to build for the next set of antlers. He needs to keep body condition up to help get through the rut in good condition. During post rut the buck needs a well balanced diet to ensure restored bone mass, deposit minerals for next summer’s antler growth, restored body mass and rebuilding the amino acid pool used to support antler growth for the following year. Mature whitetail deer will sometimes go days during the rut without eating and can lose up to 30%of their body weight due to the stress of rutting activity. Post-rut stress is responsible for more death loss in mature deer than anything, simply due to the fact that they are run down and typically have very low quality forage available to replenish body reserves. Bucks that are still growing or trying to replenish body reserves in late spring and summer will not grow the antlers that they have the genetic potential for if they are still trying to restore body condition.
How do we meet these year round nutritional needs you might ask?
- The first thing to do is work to make sure the deer density is correct for the land base. In many cases this may mean working with the DNR or wildlife biologists to get that figured out.
- Next, look at supplementing the native habitat when needed, such as during draught, winter, or when the animal has higher nutrient requirements for optimum performance than what they will get off the habitat. That means balancing food plots and supplemental feed to meet those needs.Most likely feeding a complete balanced protein/mineral/energy supplement year round makes sense because deer are either growing antlers or remodeling bone most of the time and that requires sufficient amounts of each for maximum genetic expression.
Be sure to use a supplement that compliments the native habitat and does not replace it. All of the supplemental feed in the world will not replace good habitat. If the deer you are growing are in captive habitats, it is even more critical that you offer a solid, balanced diet that offers a highly digestible fiber source. Look for diets specifically designed for breeder deer, such as Sportsman’s Choice Record Rack Breeder. It is a complete nutritional solution for penned and captive deer and is perfect solution as a single offering or fed in conjunction with additional fiber sources such as high quality forage. Antler growth is a year round job. Do your research and pick your nutrition solutions wisely. Each day of growth adds up to those amazing racks, so get started early this year with a solid program that will prove superior results. Deer with great potential deserve the best nutrition possible.