Deer Application Results and Antler growth in White-tailed Deer
By

Dan Ackerman

Rough Creek Productions

This time of year, we are all excited to find out what prestigious deer tags were drawn in our lottery that takes place in North Dakota.  It has been an excruciatingly long wait for the results.  The deer applications are due the first week of June.  This year the results came back in mid July.  The letter arrives in the mail and we’re all excited to see what color the bottom edge of the tag is; blue for buck, pink for doe.  I try to rustle the envelope and see if I can get a sneak peak through the clear opening on the front of the envelope.  The color is just out of sight, dang.  I guess the moment is here and I best be opening the letter.  Sure enough, as I suspected, I drew a mule deer doe tag.  It was my first time ever applying  for mule deer, and knowing I didn’t have any preference points built up, I figured I would end up with a mule deer doe, and sure enough I did.  I will still get a chance to enjoy the beautiful, yet rugged Badlands and will have a chance at my first ever mule deer!  I hope the rest of you reading this get a chance to hunt deer in your desired area and wish you the best in your pursuits.  Good luck!
As we are getting the lottery results in hand, it comes to mind how the deer are doing, the young ones surviving, and how big the antlers are growing.  In this piece, I’d like to discuss the biology behind antler growth in white-tails.  Not that you hunters out there reading this don’t know the difference between horns and antlers, I thought I might try to enlighten those not so environmentally inclined.
Each year, male white-tailed deer grow and shed bone formations from the top of their head known as antlers.  Most male animals in the deer family (Cervidae) have antlers.  Caribou are unique in the deer family in that both male and females typically grow antlers.  It is rare, but female white-tailed deer may also grow antlers.  This generally occurs when there is an abnormally large level of testosterone in the doe’s body. 
Deer grow antlers; they do not grow horns.  Horns differ from antlers in that horns are composed of a continuously growing bony core which is surrounded by an outer keratinous sheath.  By comparison, antlers are solid bone and they are shed and re-grown each year.  Horns are similar to antlers in that they both grow on the top of the head.
The two oval-shaped areas that grow antlers from a buck’s skull are known as pedicles.  Antler pedicles start developing on the frontal bones of male white-tailed deer fawns during late fetal development.  After birth, early stimulation from the hormone testosterone is then required for final pedicle development.  When the bucks reach nearly 5-6 months of age, the antlers begin to grow. 
Annually, deer antler growth begins between mid-March and early April.  In response to changes in photoperiod, growth hormones from the pituitary gland trigger the release of insulin-like  Growth Factor, which stimulates antler growth.  During this time, the soft growing antler is covered with hairy skin, known as velvet.  When antlers have velvet, they are full of thousands of blood vessels, cartilage, and nervous tissue.  Growth of antlers is very fast, and some deer species are capable of growing nearly 1 inch of antler a day!  Antlers continue to grow through August and September.  As day length decreases in the fall, the pituitary gland indirectly increases the secretion of testosterone and testicular volume increases.  In response to rising testosterone levels and testicular volume, antlers harden through calcification.  In this process, soft tissue is converted to bone by the depositing of minerals within the matrix of cartilage and blood vessels in the antlers.  The velvet begins to dry and sloughs off, and occasionally, bucks rub their antlers against brush to help with velvet removal.
During the rut, antlers remain as hard, polished bone with sharp tines.  Hard antlers allow bucks to fight, show posture for dominance among rival males, and displaying for does.  Between late December and early January, testosterone levels decrease and cause the area between the antlers and pedicles to weaken and the antlers are then shed or are broken off.  Once the antlers are shed, skin grows over the wound left by the cast antler.  The entire process will begin again in the spring.
Bucks will grow two small “buttons” their first year and will grow their first true set of antlers during the following spring and summer.  The second rack will be bigger than the first and with good nutrition, each set of antlers will grow even larger until the buck passes his prime (usually 5-7 years old).  Pedicle diameter also increases with age.  Older bucks typically shed their antlers before young bucks, and immature or unhealthy bucks may not shed their antlers until early spring.
Mineral requirements for antler growth exceed those of normal skeletal growth and maintenance.  In some species, antler requirements for minerals may be as high as 3 times that required to maintain the skeleton.  Mineral demand for antler growth is fulfilled from both the diet and from bone reabsorbtion. 
The diet provides the greatest proportion of calcium and phosphorus for antler growth and mineralization.  However, antler growth will never exceed genetic potential, even if a deer consumes these elements from optimum levels (so if you know the papa of the younger bucks you might have an idea of what the younger ones may look like for size and shape). 
So now that you have an understanding of what it takes to produce antlers, you have a better knowledge of why your buck’s antlers look large and in charge and hope to get that beautiful trophy of your dreams.
Good luck with your tag results and the best of wishes on your hunting escapades this fall.