Winter Nutrition of Whitetail Deer..

The Aspects of Supplemental Feeding

WHITETAIL INSTITUTE STAFF

If you have read many articles written about the effects of winter on deer, you probably have learned that in northern climates, winter is the most stressful time of the year. In fact, it is during the winter when deer herds suffer the highest death rate. Although extremely low temperatures play a part in the death rate, it is not the sole or even one of the main reasons for deer fatality. The “winter coat” of whitetails contains hair follicles that insulate the body giving deer the ability to withstand subzero temperatures.

OK, so deer can withstand cold temperatures, but what about heavy snow? Heavy snow certainly contributes to the stress of winter as deep snow makes locomotion difficult, burning up valuable energy to move from place to place. Heavy snow also covers up food sources on the ground. But one of the core reasons behind the difficulties of winter is often overlooked. This core problem is the lack of quality food sources.

The basic necessities of life are food, water and shelter. This is true for nearly all living creatures, and deer are no different. Deer can find both water and shelter in the winter but food is often in short supply. The lack of food brings about a chain reaction of events that can eventually lead to dire results for the deer herd. First, as food sources become scarce, deer begin burning energy reserves, which come in the form of fat that was deposited in the deer’s body during the spring, summer and fall. This energy is needed to perform all basic bodily functions from metabolism to breathing to walking and running. As the scarcity of food continues and energy reserves become even more depleted, deer begin to loose weight.

As we mentioned, all bodily functions require energy, but when energy is in short supply, many bodily functions begin to suffer. For example, if a deer is weak due to loss of body weight, its ability to move quickly or run diminishes, making the deer more susceptible to predators. Furthermore, deer may not have the ability to move from place to place to find what little food is available. Another bodily function that suffers from lack of energy and lost weight is the immune system. A weakened immune system can result in crippling or even death causing diseases. It is no wonder that winter can be very difficult on deer.

This is especially true for bucks. Mature breeding bucks often have the highest death rate during winter. This is due to the fact that during the rut, they have already expended much of their stored energy reserves by traveling long distances, chasing does and fighting other bucks. During this time, when excessive energy reserves are being used, little is done to replenish them as food intake drops dramatically. Basically, during the rut, bucks have only one thing on their mind and food isn’t it. It has been shown that bucks can loose up to 25 percent of their body weight during the rut and sometimes more.

After the rut, there is little to no time left to rebuild lost energy stores before the full force of winter hits. If there is little food available and/or a worse than average winter, chances are you will be finding dead bucks in the spring. Other members of the deer herd are not immune to the nutritional stress of winter either. For instance, the fawns that are just entering their first winter have just as high or even a higher mortality rate than mature bucks. This is especially true if they where born late in the year, resulting in a shorter period of time available for them to grow before winter. As for does, they are pregnant during the winter causing increased nutritional needs. If the doe does not suffer directly, her unborn fawns certainly will.

So with all of this going, how in the world do any deer live? Well, even though I have painted a bleak picture, deer are very tough and adaptive animals. Deer will consume first the more preferred food sources such as hard mast crops, food plots, etc. When they have exhausted these food sources, they begin eating browse such as dried leaves, soft woody buds of brush, dried berries, even cedar boughs if they are hungry enough. As you might have guessed, many of these less preferred food sources are also less valuable in terms of nutrition.

Again, deer are survivors, and they adapt to make it through. Their metabolism actually slows during the winter meaning that less food is needed to maintain them. They become less active during very cold periods only moving when necessary to browse for food. But even with all these survival mechanisms, deer do die virtually each winter as a result of stressful conditions.

Death is not, however, the only end result. Many, if not most deer, come out of winter in far worse condition than they entered it. The bucks must regain the weight they lost during the winter when spring roles around. It is only after this body weight is regained that the majority of the nutrients they consume can go toward antler growth. Does are nearing the final trimester of pregnancy when 60 percent of fetal growth will occur. If they are in poor condition, they must quickly regain body condition or they will likely have low birth weight fawns, which have a much higher mortality rate than fawns with higher body weights. The other possibility is that the fawns are born at a good birth weight but the doe is not able to produce enough milk to allow the fawns to grow at the rate they normally would. So, even though the deer herd may not be dieing, unseen problems can be happening.

With all this negativity, what is a deer hunter and manager supposed to do? Well, there are options. One of which is supplemental feeding. Before I go any farther into this topic, understand that, depending on what you provide, there are both pros and cons to supplement feeding.

Probably the most common winter supplemental feed is corn. Corn is relatively inexpensive and deer readily consume it. In its makeup, corn is basically starch. This starch makes corn high in carbohydrates, which gives deer a needed high energy food source. But there are problems with corn. First, the valuable starch found in corn can also cause negative effects on deer. The starch found in corn is rapidly fermented and digested in the rumen of the deer. The rumen is the largest chamber of the four-chambered stomach. In the rumen, billions of microscopic organisms digest the food that passes through. Deer utilize the by-product of the microscopic fermentation as nutrients.

Even though billions of microscopic organisms inhabit the rumen, they exist in a very precise conformity and make-up. In general terms, certain microscopic organisms digest specific food types such as starch and cellulose. Both starch and cellulose produce carbohydrates, but cellulose comes from the digestion of fibrous food sources such as plants and forage rather than corn. In most natural environments, cellulose is the majority source of carbohydrates. Therefore, more cellulose digesting microorganisms exist in the rumen. In other words, the balance is toward forage digestion.

When corn is added to deer’s diet, the rumen of the deer begins to change the balance towards starch digesting microorganisms. At the same time, the rapid digestion of starch causes a decrease in rumen pH, which negatively effects cellulose digesting organisms. Over time, deer loose some of their ability to digest forages. So they become very dependant on the corn. Now lets say the corn is suddenly taken away from the deer either on purpose or because the deer manager was not able to refill feeders. The deer return to consuming mostly forages, but their stomachs have been adapted to digest starch. It takes time for the deer’s rumen environment to change back. During this time, deer suffer greatly as they cannot efficiently digest and utilize the nutrients from the forages. In the worst-case scenario, if the deer are weak to begin with, and this transition period is too long, the deer can die. This does not usually happen but it is a possibility, and even if they do not die, they will certainly be set back.

So what do you do? First of all, if you are feeding corn, always start and end feeding periods gradually. Do not start with a huge amount and then take it away suddenly. Also, if you are feeding solely corn, be cautious of the amount you are feeding. Do not overdue corn supplementation causing it to be the deer’s main food source.

Best of all, if you are feeding corn, add a supplement to it to counteract some of the negative effects. Cutting Edge Sustain and Initiate nutritional supplements, for instance, are designed to supply carbohydrates to deer using a formulation that helps keep the deer’s rumen environment more natural. Also, these supplements contain buffering agents to help neutralize acid build up in the rumen. Cutting Edge Sustain and Initiate go a step further by using specific ingredients designed specifically for maintaining and increasing the amount of cellulose or fiber digesting microorganisms. If you are using corn, mix Sustain or Initiate at rate of 17 pounds to every 80 to 100 pounds of corn (or roughly 15-20 percent of the mix being Sustain).

Another bad situation that can arise is when a small number of feeding areas are used. If you only have 20 acres, two areas would be all right, but if you have 300 acres, more feeding areas are needed. This is especially true for areas with high deer densities. It is recommended that Cutting Edge products be used at one site per every 40 to 100 acres. This means that if you have a very small population, then one site in a 100 acres is fine. But if your population is higher, you may need two or three sites per 100 acres. The more sites you create, the more the deer will be dispersed causing less close proximity and contact. Also, dominant deer usually drive out other deer causing an uneven usage. More sites help elevate this problem. In short, error toward more sites than less.

Finally, harvest enough deer. In most areas, an increased doe harvest is needed. Supplemental feeding is designed to improve the quality of the deer herd, but it may not be successful if appropriate harvest strategies are not also implemented. You can offer all the best food sources such as food plots, minerals and supplemental feeding, but eventually, harvesting deer will be needed to maximize the quality of the deer herd.