Feeding deer is a popular activity, but this interaction requires a deep understanding of their specialized biology. Deer possess a highly sensitive digestive system that is easily overwhelmed by improper food, leading to severe illness and even death. Knowing what foods they can process and what they cannot is paramount to ensuring their health and survival.
Natural Forage and Seasonal Needs
Deer are ruminants with a four-chambered stomach, categorized as “concentrate selectors” because they prefer nutrient-dense, easily digestible plants. Their smaller rumen capacity necessitates a diet of high-quality browse, such as tender leaves, soft twigs, forbs, and hard mast like acorns. The rumen houses specialized microflora that break down cellulose, and this microflora is adapted to process specific types of forage.
The composition of this microbial community shifts naturally to accommodate the deer’s changing diet throughout the year. In spring and summer, the diet consists of high-protein forage to support antler growth, lactation, and fawn development. As autumn arrives, deer seek out foods high in carbohydrates and fat, such as acorns and beechnuts, to build fat reserves necessary for winter survival.
In winter, deer naturally decrease food intake and rely on woody browse, a high-fiber, low-energy diet. The rumen microflora adapts to digest this tougher material. A sudden influx of highly fermentable, non-fibrous food can shock the system, as it takes up to three weeks for the microbes to adjust to any significant change in diet.
Safe Supplemental Foods
The safest supplemental options mimic or augment the deer’s natural diet. Commercial deer pellets or cubes designed for wild ruminants are preferable, as they are balanced with appropriate protein content (12% to 20%). These manufactured feeds ensure the correct ratio of calcium and phosphorus, which supports bone and antler development.
High-fiber supplements like second-cut alfalfa hay or pelletized alfalfa can be beneficial, but they must be introduced slowly. Oats are a preferred and safer grain supplement compared to corn, offering a better nutritional profile. Natural, high-energy foods such as soybeans and hard mast like acorns provide caloric boosts, particularly during the pre-winter months.
Common Items Deer Must Never Eat
Many common household items and agricultural products are harmful due to their high concentration of simple carbohydrates. The most dangerous items include corn, bread, human snacks, and high-sugar fruits like apples. When a deer consumes these foods, the excess carbohydrates are rapidly fermented in the rumen, causing rumen acidosis.
This rapid fermentation promotes bacteria that produce lactic acid, which lowers the rumen’s pH level. An acidic environment destroys the specialized microflora needed to digest the deer’s natural fibrous diet and halts rumen motility. The animal becomes functionally starved, and the excess acid can damage the stomach lining, leading to dehydration and death, often within 24 to 72 hours.
Consequences of Improper Feeding
Beyond the immediate danger of rumen acidosis, supplemental feeding carries long-term ecological and health consequences for deer populations. The practice encourages deer to congregate unnaturally, which increases the risk of disease transmission. Chronic Wasting Disease (CWD), a fatal neurological disease caused by misfolded proteins called prions, is a major concern.
Infected deer shed prions in their saliva, urine, and feces, contaminating the feed and surrounding area for years. When multiple deer share a concentrated food source, CWD transmission accelerates. Artificial feeding can also lead to nutritional dependency, altering migration patterns and increasing human-wildlife conflicts, such as traffic accidents.