Deer are frequently attracted to and consume horse feed, an interaction that poses serious health risks for wildlife and potential dangers for domestic animals. This is a direct consequence of the appealing composition of commercial equine feeds, which are readily available on properties where deer forage. Understanding the specific components that attract deer, the harm they cause, and the risks to horses is essential for effective management. Horse owners must adopt informed practices to secure their feed supply and maintain the health of both their livestock and the wild deer population.
Why Horse Feed Attracts Deer
The primary allure of horse feed for deer is its high concentration of energy and palatable ingredients, which are far removed from the deer’s natural diet of woody browse and forbs. Many horse feeds, especially “sweet feeds,” contain molasses, a sticky, sugary binder that deer find highly desirable due to its intense sweetness.
These feeds are typically rich in high-energy cereal grains like corn, oats, and barley. These concentrated carbohydrates offer a dense calorie source that is easier to consume than the low-calorie forage deer rely on. This combination of easy access and potent palatability quickly draws deer into feeding areas, establishing a dangerous habit.
Health Consequences for Deer
Ingesting horse feed can be acutely dangerous, even fatal, for deer because of their specialized digestive system. Deer are ruminants, possessing a four-chambered stomach. The largest chamber, the rumen, is a fermentation vat filled with microbes designed to break down high-fiber plant materials. The deer’s digestive process is optimized for a low-starch, high-fiber diet.
When a deer consumes large amounts of high-starch grain, it overwhelms the rumen’s delicate microbial balance, leading to a rapid proliferation of acid-producing bacteria. This causes a severe drop in pH, a condition known as lactic acidosis, or “grain overload.” The resulting acidity destroys beneficial microorganisms, damages the rumen lining, and can lead to bloat, dehydration, and systemic shock.
Additionally, some specialized equine feeds may be manufactured in facilities that also produce cattle or poultry feed containing ionophores. If cross-contamination occurs, even trace amounts of these compounds, such as Monensin, can be highly poisonous to deer, affecting their heart and skeletal muscles.
Risks to Domestic Animals
The presence of deer in horse feeding areas introduces two significant risks to domestic animals, particularly horses: disease transmission and accidental poisoning.
Deer, like other cervids, can carry Chronic Wasting Disease (CWD), a fatal neurological condition caused by prions. These prions are shed through saliva, urine, and feces, meaning deer using a horse’s feed or water trough can contaminate the area. While CWD is not currently known to naturally infect horses, contamination of feed and water sources with bodily fluids from deer creates a potential pathway for spreading other pathogens and parasites.
The greatest chemical risk comes from ionophores. These compounds are often added to cattle or poultry feed to improve efficiency but are extremely toxic to horses, even at very low concentrations. Accidental ingestion of contaminated feed can lead to severe skeletal and cardiac muscle damage, causing sudden death or permanent heart failure in horses.
Preventing Deer Access to Feed
Effective prevention relies on controlling access to both the stored feed and the feeding areas. All concentrate feeds must be stored in secure, rodent-proof, and deer-proof containers, such as galvanized metal bins with locking lids. Storage areas, like feed rooms, should have tightly secured doors that are consistently kept closed.
In outdoor settings, physical barriers are the most reliable deterrent, though deer are capable of jumping fences up to eight feet high. If a full-height deer fence is not practical, consider using a double-fence system or an offset electric wire placed outside the main horse fence to discourage deer from approaching the perimeter.
Feed management should also be adjusted to eliminate leftover grain. Feeding concentrates only in amounts that the horse will consume immediately, and promptly removing any uneaten feed, will avoid attracting deer to residual food sources, especially during the night when they are most active.