WHITETAIL DEER GENETICS
The role of genetics in antler development is one of the most misunderstood areas of deer management. Many of the public think that genetics and inbreeding are the reasons that big bucks of yesteryear are no longer common place. We do know that genetics is an extremely important component of the deer management formula. However, genetics is just one of the factors that governs antler development. Age, nutrition, disease, and injury are often more important contributors to a buck’s antlers than is genetics. To understand the role that genetics plays in antler development it is first necessary to understand the contributions other factors make to a buck’s antlers. Most importantly, the animal has to have adequate nutrition. Without adequate nutrition a buck with the genetic background to become the world record white-tailed buck might be less than average.
An example of the importance of nutrition was demonstrated by a nine year-old buck that was acquired for breeding in the Mississippi State deer research facility. When acquired the buck had been in a private deer facility in Missouri and had been fed a mostly corn diet the previous year. It should be noted that corn is a very poor quality food for deer except during periods of high-energy drain during cold periods of the year. It is high in carbohydrates but low in protein (about 8 percent). On the corn diet, the animal grew an 8 point rack, had a 17 inch inside spread, 18 inch long main beams, and a gross Boone and Crockett score of about 115. After being in the Mississippi State pens for one year on a normal 16% protein ration, the animal’s antlers increased to 21 points, a 27.5 inch inside spread, 28 inch main beams, and a gross Boone and Crockett score of 210.
Age can also effect a buck’s antlers dramatically. White-tailed deer do not achieve maturity until they are 5 to 8 years of age. Studies at Mississippi State have demonstrated the average buck achieves only about 10 percent of his potential antler development by age 1.5 years (when he completes his first set of antlers as an 18-month-old buck). We also have been able to demonstrate that there is little relationship between the first year antlers and the antler development a buck will have when he reaches the mature age classes of 5 years or older. This means a spike-antlered buck has a good chance of becoming a trophy-quality adult buck.
By the time a buck has completed his second set of antlers he still has achieved only 25-35 percent of his potential antler development. At 3 years of age (few bucks live longer than this in Mississippi because of hunting pressure), a buck still only has achieved about 50 percent of his potential antler quality. It is not until 5 years of age that most bucks approach their full antler potential, and often, antlers don’t reach their maximum size until 7 or 8 years of age (for captive animals raised under ideal conditions).
Probably less than 1 out of 5,000 bucks would survive to the 6-year-old age class with the hunting pressure now across most of Mississippi. It is no wonder we don’t see the quality of bucks that existed “back in the good old days,” when hunting pressure was very low compared to today.
Another feature that may develop with age is an often-dramatic change in the conformation of a buck’s antlers. Stories abound in sporting magazines about how hunters have pursued the same buck from a young age until they developed into full maturity. It is probably the exception, however, rather than the rule that a hunter could tell he was hunting the same buck from one year to the next. In watching our captive deer develop, a high percentage will experience significant antler conformation changes by the time they reach the older age classes and bear little if any resemblance to what their antlers looked like as 1, 2, or 3 year-olds.
It is also the older age class bucks that begin to develop atypical points. A buck that has a perfectly symmetrical 8 point, as a three year-old, can conceivably have 16 or more points by age 6 years. However, some bucks develop their antler conformation at a relatively young age, and it certainly is not unusual for an 8 point yearling buck to remain an 8 point when mature. Two other factors that effect a buck’s antler conformation are injury and disease.
Injury to a buck’s antler while they are still in the velvet will often result in asymmetrical antlers with odd points, double main beams, or other abnormal characteristics. Generally, antler injuries of this type do not result in antler abnormalities the second and following years unless they occur near the base of the growing antler or to the skull. If the injury is near the base of the antler, the injury can result in abnormal development in subsequent years as well as the present year. Injury to other parts of the skeleton can also result in abnormal antler growth during subsequent years. It is well documented that skeletal injury to a hind leg will result in the opposite antler being malformed in the next and in subsequent antler growth periods. Injury to a front leg often results in the antler on the same side of the body being malformed.