By Matt Harper
Is it is just me or does it seem like sometime during the past 20 years our communities have been inundated with eating establishments? When I was a kid, we had two restaurants in my hometown, one where you had coffee (maybe breakfast if you were lucky) and the other you went to after church on Sunday for dinner (lunch for city folks). And at these diners your choices were anything that included meat and potatoes, maybe eggs at the breakfast joint. Today, I think there are more than 12 restaurants in that town with food to match any dining preference including a host of ethnic foods and good old Americana. Actually your choices are endless, which can be good or bad depending on the flexibility of your digestive tract. I am nottoo adventurous when it comes to trying new food but I did try some Thai food one time and let’s just say I spent a lot of time alone for the next few hours.
So you may be asking yourself what all this rambling about food and restaurants has to do with food plots and deer management. The answer is simple. For food plots to be effective, deer must utilize them, so it is important to have an understanding of why deer eat what they eat, and the answers can all be found in the opening paragraph; availability, taste and digestibility.
AVAILABILITY
Over the past few years I have had hunters share with me literally hundreds of different food stuffs that they swear deer love. There are the obvious ones but add to that pumpkins, watermelons, all types of landscaping plants, cattle feed and on and on. On one occasion, I had someone tell me that deer love fescue. I have never experienced this nor have I heard of deer eating fescue with regularity and certainly not as a preference. I asked him what types of forages the deer in his area have available to them. He answered with the enlightening statement that fescue was just about the only available food source.
So basically, the deer’s choices were starving or eating the fescue. I have also had hunters share with me the food plot forages that they feel work the best in terms of deer preference. A few of the forage types mentioned were a bit surprising in that they were varieties that normally do not win the deer attraction contest. After a bit more inquiry I discovered that in most cases, the forages they were growing were the only ones that would grow successfully in the type of soil in which they were planting, thus the only forages available to any degree.
In these cases, I like to use the analogy of going to a buffet. If you show up early at the buffet and you’re greeted with a plethora of choices including your favorite juicy rib eye steak, what do you think you will choose? Now let’s say you get stuck in traffic and you get to the buffet line late in the evening. The choices have been picked over pretty good and all that is left is some dried-out meatloaf.
Do you just go home? Of course not, because it has been a long time since lunch and you’re starving, so you will eat just about anything that is eatable. I used two extremes in the analogy but the fact is that with multiple choices of food, one will move progressively down the food preference scale depending on availability. Have you ever had deer seemingly disappear sometime in early fall only to find them munching on white oak acorns? Or maybe you notice less usage on your food plots for a few weeks in spring when natural browse is lush and bountiful?
While both of these examples do have the benefit of deer being able to browse in cover, it is also true that at these specific times of the year a food source that deer prefer is available. The take-home message is that it is hard to determine what food source is more preferred than another if you only have one or two choices. As the diversity of available food sources increase, so will the likelihood of determining true forage preferences.
My first experience of testing forage preference occurred several years ago when I planted my first food plot. We had an 18-acre hay field that was primarily red clover and deer were often seen browsing in the hay field. I planted a one-half-acre Imperial Whitetail Clover field near the edge of the 18-acre hay field in order to test if deer truly preferred Imperial Clover over other clovers. The first day of hunting season, I sat in a stand overlooking the bottom and was shocked to see deer move thru 18 acres of hay clover and congregate on the one-half-acre Imperial Clover field. If I had not planted the food plot, I am sure that the deer would have continued using the hay field, but when I made Imperial Clover available to the deer herd, a distinct preference was obvious.
TASTE
In the discussion of why deer eat what they eat, it would only make sense that taste would play a part in the food preference. In fact, it seems a bit obvious but in reality, the actual “taste” of the food stuffs deer prefer is somewhat less than obvious. It’s pretty tricky to get deer to fill out a taste survey as to what flavors they prefer and the incredible diversity of food that deer consume makes it difficult to pinpoint specific flavors. However, there is one type of taste that unquestionably deer are attracted to and that is sweet. Many years ago I was talking to some university researchers and they told me that the best way they could lure deer into a specific area to catch them with a net cannon was to use apple pie filling.
You may say, “Of course, it’s apples, deer love apples”. I certainly don’t disagree but I would suggest that a more exact statement is that deer like sweets. Pour molasses out on the ground and likely you will have deer attracted to that spot and for that matter, just pour sugar out and deer will be lured to that area. To further illustrate the point, deer are most attracted to apples when they ripen and their sugar content increases. Persimmons, berries and other types of soft mast are all most attractive to deer when they ripen and the fruit is at its sweetest stage. Acorns are not particularly sweet but some are less bitter than others such as white oak acorns, and it would seem that the less bitter the acorn, the more attractive it is to deer. You have all either witnessed or heard that brassicas are most attractive after a frost. The reason is that the frost forces the plant to mature and ripen which involves a buildup of sugar content in the leaves. Imperial Winter-Greens tends to be more attractive than other variety blends because the brassica hybrids used in the mix are primarily derived from vegetable (garden) varieties as opposed to the forage varieties found in most of the other brassica products and thus are less bitter. I would be remiss not to mention salt in a discussion on taste. Salt is a difficult attractant to categorize because deer are attracted to salt when they are experiencing a mineral imbalance in the body. In the spring and summer when plants are lush and vegetative, they are high in potassium. This high potassium level in the diet causes deer to crave salt in order to get sodium to balance out the potassium level in the diet. So does that mean that deer are attracted to salt because of the taste or is it more of a physiological function? It is somewhat of a chicken-or-the-egg type question, but because salt becomes less attractive to deer when plants start to mature and the potassium level drops, I would suggest that it is more physiological than purely a taste attraction. It would also appear that some types of starches and oils are attractive to deer such as those found in grains and hard mast although the actual taste attraction is less apparent.
DIGESTIBILITY
While availability and taste are two major factors affecting the food sources deer eat, the digestibility of a food source is an influencer that seems the most consistent and predictable. In order to understand the idea behind the relationship of digestibility and food source preference you first have to have an understanding of how deer digest their food. Deer are ruminants which means they have a stomach that has four sections or regions, each performing specific functions. These four sections consist of a reticulum, rumen, omasum and abomasum.
The reticulum is involved in controlling the flow of food particles either into the rumen or out of the rumen and back to the mouth. The regurgitated food-stuff bolus is then further masticated (chewed) to break down the digesta which is especially important when breaking down fibrous material. The reticulum is also called the “honeycomb” as the internal surface has the appearance of a honeycomb which acts as a filter trapping larger particulars. The omasum is less understood but is likely involved in some nutrient absorption and the control of digesta flow from the rumen to the abomasum.
The abomasum or “true stomach” functions in a similar fashion to the stomach of a monogastric (single stomach). Gastric juices found in the abomasum create a low pH environment that helps to complete the digestion of food particles to allow nutrients to be absorbed in the small intestine. The “heart” of the ruminant system is the rumen, the largest section of the stomach. The rumen of a deer is a volleyball-sized sack that is the home of millions of living microorganisms. The microbial populations found in the rumen have a symbiotic relationship with the host (deer) and are in large part what gives a deer the ability to digest fibrous material. Food particles enter the rumen and are broken down by the microbial populations resulting in the production of compounds that deer can digest and utilize. Without a healthy microbial population, deer would lose their ability to digest many of the food sources they consume. Cattle are also ruminants and therefore are often related to deer in terms of their eating habits. The difference, however, is that cattle are large ruminants where deer are small ruminants and are described this way not necessarily in terms of overall body size but rather in the size of the rumen. As mentioned earlier, a deer’s rumen is roughly the size of a volleyball but in comparison, a cow’s rumen is roughly the size of a beach ball. The larger the rumen, the more surface area and in turn the larger the population of microbial colonies. A higher population of microbial colonies gives the host animal the ability to digest forages with a greater variability of digestibility.
Therefore, cattle, being large ruminants, have the ability to digest poorer quality material with a higher NDF (neutral detergent fiber) compared to deer. NDF is a good indicator of forage digestibility for deer as it represents the total fiber content of forages. The content not found in NDF are cell solubles (starch, protein and sugars), which tend to be more easily digested. In other words, the higher the NDF, the more fibrous the forage will be and less digestible the forage will be, especially to deer. For example, cattle can derive nutrition from mature, stemmy, low-quality hay that is high in NDF where deer could literally starve on the same diet.
Put a bale of alfalfa hay in front of a cow and she will eat the entire bale where a deer will likely eat only the leaves and not the stems as the leaves are less fibrous and more digestible. When you take this knowledge and apply it to food plot forages, the less fibrous the plant, the more digestible and more attractive it will be to deer. Fiber is found in the highest levels in the structural part of plants such as the stems.
Therefore, it would make sense that a food plot with less stems and more leaves would be more attractive to deer. This solves part of the mystery as to why the deer on my farm browsed more heavily on the Imperial Clover instead of the 18 acres of hay clover. Hay clover is designed primarily for cattle production and to produce tonnage. To produce large quantities of hay, the forage needs the stem structure to support the massive growth, and since cattle can derive nutrition even from the fibrous stem, plant breeders of hay clover allow for heavy stems.
Because deer do not have as great a capacity to digest stems, Imperial Whitetail Clover was bred to be heavily leaved with smaller stems, thus making it more digestible and attractive to deer. Maturity also plays a role in digestibility. Plants that are vegetative (in the growing stage) are more digestible than mature plants. You may have noticed deer activity is always greatest in a hay field just after it has been mowed. This is because after mowing, the plant begins shooting up new tender, lush growth that is high in digestibility. So the longer a plant can stay vegetative, the longer it will be attractive to deer, which is one of the major factors that influence food plot design at the Whitetail Institute. The preference for new growth also explains why deer utilize natural browse most heavily in spring.
CONCLUSION
Deer can be unpredictable and I am in no way saying that you can tell what a deer is going to eat 100 percent of the time. I have seen deer eat things with no logical reason as to why they are eating that food source. However, if you keep in mind the three factors we discussed —availability, taste and digestibility — you will be able to accurately predict more times than not what deer prefer to eat at certain times. And that prediction may very well give you an advantage when next deer season rolls around.
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