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. Whitetailed 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.
Disease also can cause antler growth to be abnormal. The bluetongue and hemorrhagic diseases often occur during late summer when antlers are growing and cause antler growth to cease at that time. Bucks to which this occurs often have blackened, pithy antler tips for that year. Disease can also permanently restrict potential antler development. Nutritional and hemorrhagic can damage the digestive tract and prevent an animal from ever obtaining its optimum body condition and antler development.
Given proper nutrition, age and no injuries or debilitating diseases, it is genetics that determine the final development of a buck's antlers! Two deer can be raised together to 7 years of age under optimum nutrition and conditions. One may become a Boone and Crockett deer while the other may only develop into a mediocre 6 or 8 point deer. In this case, the genetic makeup Mother Nature gave them would determine the antler development. We know there are some geographical areas that consistently produce better quality antlers than others. We also know that, with the exception of antler injury, it is genetics that determines whether a buck will have typical or atypical antlers. Our research has shown that a buck does not always transmit his antler qualities to his offspring. For example, a buck with very poor antler qualities may produce offspring with very good antler qualities and vice versa. This means there is very little that can be done to practically manage genetics in a wild deer population because we cannot determine which deer will pass the superior genes to its offspring. Additionally, even if we could select a "superior" buck, 50 percent of the offspring's genetic information is supplied by the doe, and there is no way to identify the superior doe! Research at Mississippi State has demonstrated doe's are equally, or more important, than bucks to determining the offspring's antler qualities. This does not mean that we will not manage genetics of the white-tailed deer in the future. In fact, it is probable that we will do so through genetic introduction. However, we first need to better understand through research, such as that being conducted by Mississippi State , what is prudent and wise to do when considering manipulation of genetics in wild populations.
Crossbreeding Michigan and Mississippi Deer, a Research Update
In 1989, the first Michigan deer made the long journey from Houghton Lake , Michigan , to Starkville , Mississippi . A year later a group of Mississippi deer went north to Michigan . We have answered some of our questions in the intervening years. First, we have found that deer moved from the northern U.S. to the southern U.S. may have a difficult time adapting. Of 5 male and 10 female Michigan deer originally transported to the Mississippi State University research facility, only 5 females survived to 1994. Six of the Michigan deer died as fawns from the viral hemorrhagic disease, and 4 deer died at 2-3 years of age from pneumonia. In the same period, none of the native Mississippi deer in the Mississippi State facility died from hemorrhagic disease and no similar cases of pneumonia were seen. This suggests that the Michigan deer lack immunities to some of the diseases common in the southern U.S.
Surprisingly, the southern deer seem to have adapted quite well to the northern U.S. Although three Mississippi deer died from incidental injuries soon after their transfer to Michigan , most adapted very well to the colder climate.
The most obvious visual difference between the two races of deer is skeletal size. On average, the Mississippi deer are considerably smaller in stature than their northern counterparts. Within the same age classes, Michigan deer outweighed the Mississippi deer by an average of 25 to 30 lbs. for does and 25 to 50 lbs. for bucks.
Although body size differences were dramatic, other less obvious differences may ultimately prove more significant to the biology of the white-tailed deer. Two events we are paying close attention to are fawning dates and the timing of antler events.
One surprise finding was that the Mississippi buck in Michigan was not able to breed Michigan does at their normal breeding time. The buck was not ready to breed the does in their normal first heat cycle. As a result, the does bred by the Mississippi buck had fawns one month later than normal.
Except for those Michigan does bred by the displaced Mississippi buck, fawning dates of Michigan does have averaged almost 7 weeks earlier than Mississippi does. However, both Mississippi and Michigan does had fawns an average of 3 weeks earlier when in Michigan than in Mississippi .
Timing of the rut can be related to the buck's physical performance. This is seen when we examine the timing of antler events. Hardening of the antlers and shedding of antler velvet averaged almost a month later for Mississippi deer than Michigan deer, whether in Mississippi or in Michigan . Similarly, the casting of antlers averaged a month later for Mississippi deer.
Interestingly, the seasonal event of molting from winter-to-summer and summer-to-winter coat has not been different between the two races of deer. However, we have seen later molting for both races of deer when in Michigan compared to Mississippi , with molts occurring almost three weeks earlier in Mississippi than in Michigan .
It is well documented that daylight length regulates the timing of molting and reproductive events of deer. The preliminary findings of this study suggest that the photoperiod differences between the two locations are causing these normal seasonal events of reproduction and molting to occur three weeks earlier or later, depending on the geographic location. However, what is surprising about our results is that reproduction appears not only to be governed by photo-period signals, but also by a genetic clock which causes the two races of deer to respond at different times to the same photoperiod signals. The test of this finding will result in how the crossbred offspring from the two races of deer respond.
Initial results of reproductive activity from crossbred offspring seem to be confirming a genetic linkage is occurring for reproductive timing. The crossbred does followed so far have had fawning dates between the two parent races.
Much research remains to be conducted in the area of genetics. The results should provide many exciting new discoveries about the importance of genetics and environment to the white-tailed deer.
What is the importance about this study to the average sportsperson? The answer relates to the practice of wildlife management in every state in the country. All states have had native wildlife introduced, or reintroduced, at some time, from other geographic locations. Some of these relocations have been harmful and some beneficial to the gene pools of resident wildlife species. It is foolhardy to think that genetics will be an unimportant component of wildlife management in the future. In fact, genetics have historically been important on a large scale. With this in mind, it is extremely important we find out how genetics effects traits important to survival, reproduction, growth, and other qualities of wildlife. What better place or species to start with than our favorite game species, the white-tailed deer! Hopefully, the results of this and other studies will allow us the opportunity to wisely manage attempts involving the genetic manipulation of our native game species.
Survival Rate and Cause of Death of Adult Bucks in Mississippi
Quality Deer Management (QDM) is being practiced on many hunting clubs and on public lands in Mississippi . Because with QDM young bucks are passed over by hunters and allowed to live to older age classes, it is important to know the survival rates of adult bucks when subject to hunting mortality. A study funded by Mississippi Department of Wildlife and Fisheries (MDWFP), participating hunting clubs, Anderson Tully Company, and Deer Hunting Magazine, has helped to address this question.
We implemented a study to find the answer to the question, "what happens if young bucks are let go by hunters?" From 1989-1994, a total of 320 deer were captured on 16 study areas. Radio transmitters were placed on 167 adult bucks. Mortality occurred for 92 of the transmitter collared animals with 72 (78 percent) dying from gunshot, 12 (13 percent) from unknown causes, 6 (7 percent) capture related, 1 (1 percent) from meningitis and 1 (1 percent) from pneumonia.
These preliminary results indicate that adult bucks in Mississippi have very low natural mortality rates. If protected from hunting mortality as yearlings, there is an extremely high probability that the same buck will live to an older age class. Thus, protecting these young bucks should not greatly reduce the hunter's bag. Instead, protecting young bucks improves the quality of the deer herd and the hunting experience.
What Has Happened to the Rut?
The two men in the coffee shop were in a dilemma. They had always scheduled a week's vacation the first part of January. For many years, that was the week the deer moved the most and hunting seemed at its best. The last couple of years, however, the deer hunting had not been the same. In earlier years, they could always count on the bucks to be chasing does at that time. It seemed things changed the year after they had agreed to follow a biologist's recommendations and start harvesting many does. Now they were not so sure they had done the right thing. They were seeing fewer deer and the hunting definitely did not seem as good as before. However, they had to admit the deer they did harvest were in better condition and all the does seemed to have two fawns.
The conversation was just about to change subjects when another man who belonged to their hunting club entered the restaurant. They had not seen their friend since before last hunting season. The conversation turned back to hunting, and they asked what sort of hunting season their friend had. They were surprised to hear that he thought the last season had been the best he ever had. He had always taken his vacation the week before Christmas. He could not remember when he had seen so much deer activity. He had killed a heavy-beamed 10 point on Christmas Eve morning as it chased a doe past his stand.
The situation just described is happening all over the South. The dates might range from October through January, but the rut is changing. To understand why, we need to examine what determines the rut.
The rut is the period when breeding occurs. It is determined by when the does enter estrus, or heat. In much of Mississippi and Alabama the rut can be as late as the first couple weeks of January. Recent research has indicated that the rut is controlled largely by genetics. In fact, deer can be found somewhere in North America breeding in every month of the year.
We know that the rut can be modified by changing the photoperiod, or hours of day-length, a deer is exposed to. This is because of a photo-sensitive gland known as the pineal gland found at the base of the brain. This gland is actually derived embryologically from a third eye. The pineal gland controls the reproductive centers of the brain and serves as a "biological clock." We believe that genetics sets this biological clock, but photoperiod regulates when the clock starts or stops.
A scientist named Richard Goss demonstrated the importance of photoperiod. Dr. Goss found that if deer were placed in controlled rooms and the number of dark versus light hours in the day were regulated, the reproductive period of deer could be changed. In fact, deer transported to the Southern Hemisphere ( New Zealand or Australia ) from the Northern Hemisphere will actually change their reproductive cycles by 6 months.
Despite the importance of photoperiod as a regulator of the rut, photoperiod changes do not explain the changing rut currently experienced by many hunting clubs. Annual changes can occur due to slight changes in the weather, but it does not account for the magnitude of change we see in some areas. In fact, although the timing of the rut has changed for some hunting clubs, others in the same areas have not changed. So what is causing this change?
Many clubs harvest an average of 70 percent of the antlered bucks annually. This pressure on adult bucks produces a heavy distortion of sex ratios, and we believe this results in too few bucks to breed the receptive does on their first estrous cycle. When a doe comes into estrous, or heat, she is receptive to a buck for a period of about 24 hours. If she is not bred in that period or does not become pregnant, she will not come into estrous again for another 22-28 day period.
We have seen a changing rut where hunter harvest has shifted from heavy buck and light doe harvest to heavy doe and moderate buck harvest. An early 1990's study at Mississippi State University found that hunting clubs that harvested at least as many does as bucks had average breeding dates at least 2 weeks earlier than those that did not have equal sex harvest. Some clubs that have been practicing equal-sex deer harvest for many years have actually shifted the rut as much as a month earlier.
Hunting clubs now engaged in QDM (showing restraint in harvest of yearling and 2-year old bucks and harvesting an adequate number of does) have seen many positive changes in their deer herd. Not only has it provided more venison for the table, but also the chance to harvest 3-year old and older bucks in numbers never before experienced. Because fawning is earlier, fawns develop earlier and experience higher survival and better growth rates.
With proper management, the end result is everyone wins. Hunters have an earlier rut to hunt. The deer herd and habitat are in better condition. It seems contrary to what many hunters were raised to believe; i.e. shooting as many does as bucks. However, we now know doe harvest is required if we want to maintain deer herds in their most productive state. Most deer herds in the South have increased to the point that they will seriously damage their habitat, health, and productivity unless adequate antlerless harvest is practiced. Hunters should be aware that adequate antlerless harvest will change the period of the rut. Thus, start now in planning an earlier vacation for the future!
The information above was taken from MSUcares.com , Mississippi State University Extension Service
