Whitetail Deer Nutrition

by

Michael Foster??

Sr. Associate Consultant

Davey Resource Group

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Whitetail deer are probably the most economically important large game animal across the United States. That being said, the management of this species has become more intensive as the amount of suitable habitat has decreased due to the expansion of the human population. Furthermore, as the desire for quality deer of the quantity of deer increases, so too will the intensity at which this species will have to be managed. This will require a deeper understanding of the nutritional requirements that effect body size, reproduction, and survival.

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The truth is, the nutritional requirements of whitetail deer are not fully understood. While some of the nutritional needs are similar to those of domestic ruminants, most are profoundly different; therefore, caution must be taken when comparing domestic ruminant nutrition to that of whitetail. Nutritional needs of deer have to be confronted on a seasonal basis in correspondence with both physiological changes within the population and the nutrients available to them. ?Often times the nutrients needed for one season is a result of deficiency from a previous season. While deer can survive for a relatively long period of time on little to no food, the effects of nutritional deficiency can be seen for up to two years after the deficiency occurred: this often results in decreased body weights, decreased birth weights, and decreased antler mass across the population. Armed with that knowledge managers have to manage deer populations so that there is enough natural forage to meet the population’s nutritional needs, and in some instances provide supplemental food sources.

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Whitetail deer are browsers, meaning they feed on a variety of different forages in varying quantities. That being said, deer do not really have one particular food that dominates their diet. Food selection depends on palatability and availability; therefore, variety is key to a healthy herd. Much like us, nutritional requirements center on proteins, fats, carbohydrates, vitamins, minerals, and water. For the sake of space this article will focus on the three macronutrients.

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Proteins are needed for body growth and maintenance, reproduction, lactation, and antler growth. While the amount of protein necessary depends on age, sex, life cycle, and season, the necessity of protein supplementation is a highly debated topic among whitetail biologists. On one side of the spectrum there are those who believe that a deer’s natural diet provides sufficient protein levels to promote growth and since deer can only process around 17% protein at a time anything more than this is a waste. On the other end are those who believe that to maximize genetic potential a high protein diet is necessary year round and the only way to do this is through supplementation.

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Fats and carbohydrates can both be lumped into the energy category. ?Energy is a component of management that often gets overlooked. Like protein, energy requirements are cyclic and are guided by age, growth stage, gestation, lactation, movement, temperature, and antler development. While energy availability is always important, it becomes especially critical during the late summer and throughout the fall. During this time bucks and does are preparing for breeding and pregnancy so energy intake is increased to put on fat stores to endure winter and deliver adequate nutrition to developing fetuses. Just as we discussed a few weeks ago with cattle nutrition, the mother’s nutritional state greatly affects the condition of her fawn(s). Inadequate energy supplies lowers fat stores and can lead to a state of catabolysis where the body is feeding off of muscle tissue due to depletion of fat stores. This can lead to a vicious cycle of nutritional deficiency for years to come.

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While the nutritional requirements of deer are not fully known we do know that basic protein and energy requirements must be met in order to produce quality animals. Healthy deer have increase body weights, decreased disease occurrence, and stable populations. Populations in poor health often cycle up and down in numbers; often shooting above carrying capacity then falling drastically below. While nutritional supply is not silver bullet answer to situations like this, it is a step in the right direction.