Corn and Corn Oil for Horses: Benefits, Types & Feeding Guide

Corn is an economical energy source found in many complete feeds for horses. Corn is also sometimes fed as a standalone concentrate for horses that need additional calories in their diet, such as exercising horses, growing horses, or mares in the late stages of pregnancy or early lactation.

Corn products come in many forms, including whole, cracked, meals, oils, silages, and syrups. Different forms of corn provide differing nutrient compositions, making it a versatile feed ingredient for livestock.

However, due to the high starch content of corn grain products, they should be incorporated into the diet cautiously and avoided when high starch or energy intake is unnecessary. Feeding too much corn poses a risk of digestive and metabolic issues.

Grain-based feeds like corn should always complement your horse’s forage, not replace it. Horses should ideally be fed a balanced, forage-based diet with concentrates added only as needed to meet their specific nutritional requirements.

Corn for Horses

Corn (Zea mays L.) is a common agriculture crop that belongs to the grass family. While corn originated in the tropics, it can be grown in a wide range of climates.

The United States boasts the highest production of corn in the world, with 38% of global production occurring in the country. ^[1]

Corn is cultivated for a wide variety of purposes, such as human and animal foods, as well as biofuel production and more. While it can be used for many purposes, corn is one of the most productive food-producing plants, making it an important food source for humans and livestock animals alike. ^[1]

Many types of corn products are fed to horses, including:

• Whole corn
• Cracked corn
• Corn meal
• Steamed corn
• Steam-flaked corn
• Micronized corn
• Popped corn
• Corn oil
• Corn silage
• Corn distiller’s grain
• Corn cobs
• Raw corn
• Corn syrup

The nutrient profile of corn depends on its processing method. Products like cracked and steam-flaked corn have nutrient profiles similar to whole corn, though their digestibility may be altered. Conversely, corn products like corn oil and corn syrup have a significantly different nutrient profile.

Table 1. Nutritional composition of select corn products compared to oats and barley. ^[2][3][4]

Forms of Corn for Horses

The wide variety of corn products on the market and their differing nutrient profiles can make it difficult to determine whether and which type should be included in your horse’s diet.

Usually, horse owners add corn products to equine diets to increase calorie intake. Determining the best source of calories for your horse can help make the choice simpler.

Adding Starch with Corn Grain

Products such as shelled (whole) corn, processed corn grain, and ear corn (corn on the cob) provide energy mainly in the form of starch. This is similar to other grains such as oats and barley.

Although corn tends to have a higher energy and starch content compared to oats and barley, feeding corn results in a similar glucose and insulin response to other grains. ^[5]

Corn Processing

A corn kernel consists of a starch-rich endosperm surrounded by a fibrous hull. The fibrous outer layer of corn has lower digestibility compared to the starch in the endosperm.

This means that the energy from the starch is more readily available to the horse, while the fibrous hull provides less nutritional value and is harder for the horse to break down. For this reason, processing corn to disrupt the hull can make the starch inside more available for digestion. ^[6]

Starch can be digested in both the foregut and the hindgut of horses. Digestion of starch in the small intestine results in absorption of glucose, a potent energy source.

Starch that is not digested by enzymes in the small intestine travels to the hindgut, where starch-fermenting microbes consume it to produce volatile fatty acids and lactic acid. Although volatile fatty acids do serve as an energy source for horses, the lactate produced alongside starch fermentation can disrupt the hindgut microbiome and even lead to hindgut acidosis.

Improving the foregut starch digestibility of grain allows the horse to extract more energy in the form of glucose, potentially reducing the risk of excess starch reaching the hindgut, where it could cause digestive problems.

Common processing methods for grains in horse feeds include mechanical, thermal, and thermo-mechanical treatments. ^[6]

• Mechanical processing: Rolling, crushing, or grinding grains can break their fibrous shells, making starch more available for digestion.
• Thermal processing: Roasting or micronizing grains exposes them to high temperatures and pressures, which expands the grain and gelatinizes starch to improve its availability.
• Thermo-mechanical processing: Flaking, popping, and extruding combine mechanical and thermal processes to both break the outer shell of grain kernels and gelatinize the starch to improve its availability.

When comparing processing methods like cracking, grinding, and steam processing of corn, steam-flaking often results in a greater glucose response, indicating improved starch digestibility. ^[7][8] However, other research examining the effect of finely grinding, steaming, micronizing, steam-flaking, and popping corn showed no difference in glucose and insulin response. ^[9]

It’s worth noting that in some cases, the digestibility of starch in corn is improved with processes like micronizing, but there is no difference in glucose and insulin response. ^[10]

Adding Fat with Corn Oil

Similar to other oils such as soybean, canola, and flax oil, corn oil is a rich source of calories from fat.

Oils are composed of nearly 100% fat. Corn oil is primarily composed of polyunsaturated fatty acids (59%), but also contains monounsaturated fatty acids (24%) and saturated fatty acids (13%). ^[11]

Closer examination of the polyunsaturated fatty acid profile of corn oil reveals that it predominantly comprises the omega-6 fatty acid linoleic acid, with only a small amount of the omega-3 fatty acid linolenic acid. This gives corn oil a very high ratio of omega-6 to omega-3 fatty acids, at 83:1. ^[11]

This omega-6 to omega-3 ratio is considerably higher than other common oils used for horses such as soybean oil (4:1), canola oil (2:1), and flax oil (0.3:1). ^[12][13][14]

Adding Sugar with Corn Syrup

Corn syrup is created by breaking down the starch from corn to its constituent glucose molecules. This produces a sugary syrup mix of glucose from corn.

Corn syrup can be used to sweeten commercial feeds to improve their palatability. It can also be used as a top-dressing for unsweetened feeds to encourage consumption.

Due to its very high sugar content, corn syrup should be used sparingly to avoid glucose overload. It should also be avoided in horses that are sensitive to sugars or excess calorie intake, such as horses with metabolic problems or easy keepers.

Adding Fiber with Corn Silage

Corn silage is made by cutting corn plants (stalk, leaves, grain, and cob) and fermenting them. This produces an energy-dense forage crop that provides calories mainly in the forms of starch and fiber.

Corn silage is more commonly fed to dairy cows, who have very high energy needs, but it has also been investigated as a feed source for horses. ^[15]

Though there is no available literature comparing corn silage to other silages for horses, corn silage does appear to be digestible, and an acceptable forage source for young and mature horses. ^[15][16]

However, due to its high energy and starch content, corn silage should be incorporated into the diet carefully to avoid introducing nutrient imbalances that may cause excessive weight gain, growth, or metabolic issues.

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Benefits of Corn for Horses

Because of its high energy density, corn can be used to increase the energy content of the diet. This may be helpful to support weight gain or weight maintenance in times of high energy demand. Corn grain is not a good source of added energy for every horse, but it can be used carefully to boost the energy and starch content of the diet when needed.

Performance Horses

Performance horses, particularly those engaged in high-intensity activity, may benefit from calorie supplementation in the form of starch from corn.

Starch can help restore glycogen, which is the stored form of glucose in muscles. When horses engage in high-intensity exercise, they often rely on glucose from glycogen to fuel activity.

Unfortunately, unlike humans, horses have a very slow rate of glycogen replenishment that is not significantly enhanced by feeding a high carbohydrate meal after exercise. ^[17]

Some studies suggest that diets high in sugar can reduce glycogen use, while higher starch intake may accelerate glycogen replenishment in horses. However, more research is needed to determine if a high-starch diet can effectively maintain glycogen stores and to identify the appropriate starch levels that balance glycogen replenishment with the potential negative effects of high starch intake, such as digestive issues.

As an alternative to feeding a high starch diet, corn oil can increase the calorie content of your horse’s daily ration without adding sugar and starch. In addition to being a good source of calories, corn oil may be helpful for horses with gastric ulcers, a common condition among performance horses.

Growing, Pregnant, and Lactating Horses

Mares in the late stages of pregnancy and early stages of lactation have some of the highest energy requirements of any horse.

To meet their energy needs, voluntary feed consumption often increases during this period. This increased feed intake makes it easier to add more starch sources to the diets of broodmares to increase calories without raising the overall starch content too high.

Growing horses also have higher energy requirements relative to their body weight to meet their developmental needs. However, they have limited feed intake due to a smaller body size and need to be more wary of consuming excess starch. While corn grain may provide high energy density, it should be used sparingly for growing horses to avoid developmental issues.

Regardless of the horse, corn should always be added to the diet carefully, as too much starch can cause digestive and metabolic problems.

Corn Oil for Gastric Health

Corn oil may have functional benefits as a component of equine diets. Research shows that corn oil can reduce gastric acid output and increase prostaglandin E2 levels in horses with existing ulcers. Both of these factors are associated with supporting gastric health. ^[21]

However, other experimental results show corn oil may not be effective at preventing ulcers on its own. ^[22] Thus, while corn oil may be considered as a dietary addition to support gastric health, it should be used alongside appropriate dietary measures, management practices, and veterinary care to resolve gastric ulcers.

Other research also suggests corn oil may increase the effectiveness of Ponazuril treatment for horses with Equine Protozoal Myeloencephalitis. ^[23]

How to Feed Corn to Horses

Corn grains and oils can be added to your horse’s feeding plan to increase its energy density. However, determining the right amount and the most suitable type of corn product can be challenging.

How much is too much? And which corn product will best meet your horse’s nutritional needs?

The tables below offer example diets for incorporating steam flaked corn or corn oil into the diets of different classes of horses.

Many horses can meet their energy and protein needs with forage alone and do not require any corn products added to the diet. Some exercising horses benefit from moderate inclusion of corn-based feeds or corn oil to increase calorie consumption.

For those with higher protein requirements, corn may fall short as a concentrate. Adding protein sources such as alfalfa or soybean meal can help to meet the needs of these horses.

In all cases, corn and forage alone will not meet horses’ vitamin and mineral requirements. Therefore, a complete vitamin and mineral supplement should be used to ensure their nutrient requirements are met to support health, longevity, and performance.

In all cases, feeding corn and forage alone will not provide sufficient vitamins and minerals for horses. To ensure their nutrient requirements are fully met, a complete vitamin and mineral supplement should be included in your horse’s diet.

Additionally, sodium is often lacking in forage and corn. Therefore, all horses should be fed salt to meet their sodium requirement and encourage water consumption.

Performance Horses

For performance horses, who are prone to gastric ulceration, the goal of a diet with corn inclusion should be to meet energy needs without excessively increasing starch levels.

Combining corn grain with oils, whether corn oil or another type of fat supplement, can help to balance energy intake from different nutrient sources.

Table 2. Sample diet for 500 kg (1,100 lb) horse in heavy exercise

In this sample diet, Mad Barn’s Omneity® Pellets are included as a comprehensive vitamin and mineral supplement to balance the horse’s diet. Feeding Omneity® helps to support overall health and exercise performance, promote optimal hoof condition, and maintain a strong immune system.

Pregnant Mares

The energy requirements of mares in late gestation are not as demanding as those of horses in heavy exercise. For that reason, a more moderate amount of corn grain alone, or a combination of corn oil and alfalfa pellets can meet their energy needs.

Table 3. Sample diet for 500 kg (1,100 lb) mare in late gestation (10 months)

Lactating Mares

Mares experience their highest energy demands during the early stages of lactation. Ensuring these requirements are met helps maintain their body condition and ensures adequate, high-quality milk production to support the growth of their foal.

Given the very high energy demands, the goal of a corn-supplemented diet for a lactating mare is to meet calorie needs without greatly oversupplying starch.

Additionally, lactating mares have elevated protein needs, which requires the inclusion of high-quality forages in their diet. The example diet below uses a combination of corn grain and corn oil to meet energy needs, while high-quality grass hay and alfalfa hay are used to fulfill the mare’s protein needs.

Table 4. Sample diet for 500 kg (1,100 lb) mare in early lactation (1 month)

Growing Horses

Growing horses have high energy needs relative to their body weight. Providing adequate energy is critical for supporting their rapid growth and development.

When supplementing their diet with corn, the goal is to meet these energy demands without significantly exceeding the horse’s starch requirements, which could lead to digestive issues and other health concerns.

Growing horses also have a higher protein requirement, which necessitates additional supplementation. The example diet below incorporates both corn grain and corn oil to meet the horse’s energy needs. Alfalfa hay is also added to ensure that the protein requirements are fulfilled.

Table 5. Sample diet for yearling horse with a 500 kg (1,100 lb) estimated mature weight

When to Avoid Feeding Corn to Horses

Although corn provides a good source of energy for some classes of horses, others may not benefit from corn supplementation. Due to its high energy density, corn should not be fed to overweight horses or easy keepers.

Corn also presents risks for horses with a history of gastrointestinal issues, such as colic or hindgut acidosis. Furthermore, corn is low in fiber compared to other forages, which is essential for maintaining healthy gut motility and microbial balance in horses.

If including corn in your horse’s diet, ensure it is fed in appropriate amounts and divided into multiple small meals throughout the day. This approach helps prevent issues that can arise from excessive starch consumption in a single meal.

Consulting with an equine nutritionist can help tailor your horse’s diet to meet their energy needs while safeguarding their digestive health.

Metabolic Issues

The main concern with feeding corn to horses as an energy source is its high starch content. This makes corn unsuitable for horses with metabolic issues, such as:

• Insulin resistance
• Polysaccharide Storage Myopathy
• Equine Metabolic Syndrome
• Pituitary Pars Intermedia Dysfunction (PPID; formerly known as Cushing’s Disease)

A high starch intake can rapidly spike blood sugar and insulin levels, also potentially leading to starch overflow to the large intestine. High insulin concentrations are associated with an increased risk of laminitis. ^[24] Starch overflow to the large intestine can also lead to issues such as hindgut dysbiosis and endotoxemia, potentially reducing the blood flow to the hooves and triggering laminitis. ^[24]

While different types of corn may vary in digestibility, current research does not provide clear evidence that processing methods significantly impact glucose and insulin responses in horses. ^[27][9] Therefore, no specific form of corn grain appears to reduce starch delivery to the hindgut and limit the risk of digestive-related laminitis.

While adding fiber to mixed meals has been shown to improve glucose tolerance in other species, the addition of fibers such as pectin and lignocellulose to a meal containing corn did not result in improved glucose or insulin responses in horses. ^[25]

While adding fiber to mixed meals can improve glucose tolerance in other species, research shows that adding fibers like pectin and lignocellulose to meals containing corn does not improve glucose or insulin responses in horses.

Corn is also a source of plant-derived micro-RNAs, which are absorbed by the horse’s body and delivered into circulation and skeletal muscle. Some of these micro-RNAs are linked to obesity and metabolic disease. ^[26]

Given the potential negative impact of corn on metabolic health in horses with weight and metabolic issues, it is advisable to avoid corn for any horse with glucose and insulin dysregulation or those that are prone to weight gain.

Given the potential negative effects of corn on metabolic health, it is recommended to avoid corn in the diets of horses with glucose and insulin dysregulation or those prone to weight gain.

Reactivity

High starch intake is also associated with increased reactivity or ‘hot’ behavior in horses. ^[27][28] This makes corn and other high-starch grains a poor choice for reactive horses.

Replacing grains with fat sources, such as corn oil, is one way to increase calorie intake without affecting reactivity. ^[29]

Inflammation

Corn products should be avoided for horses with a history of inflammatory issues. Consuming both corn grain, or corn oil, may lead to increased inflammation in horses.

High-starch diets, such as those with large amounts of corn, can increase post-feeding inflammation. ^[30] In addition, when compared to fish oil, corn oil results in elevation of some inflammatory markers. ^[31]

Mold and Mycotoxins

Molds are collections of fungi that thrive in moist conditions with access to oxygen. Some molds produce substances called mycotoxins, which are toxic to horses.

Improper storage of corn grain can lead to wet conditions that lend to mold infestation. Common mycotoxins found in corn include: ^[32]

• Aflatoxins
• Fumonisins
• Trichothecenes
• Zearalenone

These mycotoxins can lead to adverse health effects in horses such as: ^[33]

• Liver dysfunction
• Equine Leukoencephalomalazia
• Endocrine disruption
• Lack of appetite
• Gastrointestinal disruption
• Central nervous symptoms
• Salivation
• Tremors

To protect your horses from mycotoxin poisoning, it’s important to purchase corn and grain-based feeds from reputable distributors that test for mycotoxins and store their products carefully in a dry space.

When storing corn-based concentrates at home, be sure that it is not exposed to moisture, and discard any corn that becomes damp.

Summary

Corn can be processed into several different products that are useful for supplementing energy in horse diets. However, not all horses benefit from corn, and corn products should be added to your horse’s diet with care to avoid creating nutritional imbalances.

• Corn grain and corn oil are common products added to equine diets to increase calorie intake.
• Exercising, growing, pregnant and lactating horses may benefit from calories provided by corn. Corn grain should be added to the diet sparingly to avoid starch overload.
• Avoid adding corn (especially grain) to the diets of horses with metabolic issues, weight gain issues, high reactivity, and inflammatory conditions.
• When feeding corn, it’s important to ensure it has been milled properly and stored in a dry place to avoid mold contamination and mycotoxin exposure.