How Horse Feed Affects Emotional Health and Behavior

Feed ingredients and feeding practices can have a noticeable effect on a horse’s energy level, behavior, and emotional well-being.

Owners may notice changes in behavior after a dietary adjustment, such as increased reactivity, excitability, or difficulty focusing, and describe the feed as making their horse “hot.” Conversely, an unbalanced diet or inadequate nutrient intake may leave a horse appearing dull or low in energy.

Although nutrition is unlikely to fundamentally change a horse’s temperament, starch and sugar intake, forage quality, meal size, digestive comfort and feeding routine can all influence how a horse feels and responds to its environment. Understanding how feed can—and cannot—affect behavior helps owners separate common myths from evidence-based nutrition principles.

Read on to learn how diet can affect equine behavior and emotional health, along with practical strategies for supporting a healthier and more emotionally balanced horse.

Can Certain Horse Feed Ingredients Affect Behavior and Emotional Health?

Horse feed does not typically change a horse’s underlying personality, but it can influence how the horse feels and responds to its surroundings.

Nutrition can affect equine behavior through three primary pathways:

  • Energy levels: The type and amount of energy provided 
  • Digestive comfort: How feed ingredients, meal size and feeding practices affect the gastrointestinal tract 
  • Nutritional balance: Whether the diet is deficient, meets, or exceeds the horse’s calorie, protein, vitamin and mineral requirements

For example, a meal high in rapidly digestible sugar and starch may produce sharper fluctuations in blood glucose and insulin than a meal based primarily on fiber and fat. Large starch meals can also overwhelm the horse’s ability to digest starch in the small intestine, allowing more to reach the hindgut.  This can alter fermentation, lower hindgut pH, and contribute to physical discomfort. Research has associated high-starch diets with changes in the equine hindgut microbiome and increased signs of anxiety or reactivity during certain stress tests.

Inadequate nutrition can also conversely affect behavior. A horse that does not receive enough calories, quality protein, vitamins, or minerals may appear dull, lethargic, or reluctant to work. Nutrient deficiencies can also interfere with normal muscle function, energy metabolism, and recovery. However, it's important to remember low energy can also be due to pain, illness, anemia, poor fitness, and other health concerns, which can produce similar signs.

How Starch and Sugar in Horse Feed Affect Behavior

Sugar and starch are nonstructural carbohydrates (NSCs) found in cereal grains such as corn, oats, and barley, as well as hay and pasture grass, and are a common reason for a feed to affect behavior. Some horses tolerate NSCs well, while others appear more sensitive to higher sugar and starch intake.

Horses need carbohydrates for energy, but NSC intake needs to match workload, metabolism, and individual tolerance. A racehorse in intense training may require more rapidly available energy from carbohydrates than a lightly worked pleasure horse, for example.

When a horse consumes more energy than its workload demands, it may become “hot,” unfocused, and prone to other behaviors like spooking or bucking. These behaviors may also occur when the feed’s NSC level is unsuitable or large grain-based concentrate meals are fed all at once, causing spikes in energy.

Higher molasses levels can increase the sugar content of horse feed and may contribute to behavioral changes in some horses. Feeds commonly called “sweet feeds” are textured livestock or equine feeds that typically contain about 5% to 12% molasses.

Diet may also influence behavior through the gut-brain relationship. High-sugar and high-starch diets can disrupt the hindgut microbiome and increase the risk of digestive discomfort or ulcers. In some cases, a horse that appears unusually reactive, irritable, or emotional may actually be responding to gastric or hindgut discomfort rather than excess energy alone.

Choosing a feed that is lower in starches and sugars and higher in fiber and fat may support steadier energy, while dividing grain concentrates into smaller meals can help reduce digestive overload.

However, the complete formula, recommended feeding rate, and total diet matter more than any single ingredient, and no feed or management strategy can guarantee calmer behavior.

High-Sugar Pasture Grass: Can it Influence Horse Behavior?

Pasture grass contains natural sugars, and its NSC content can fluctuate based on plant species, maturity, sunlight, temperature, drought, and frost. Lush pasture may also provide more calories than a horse in light work requires, contributing to weight gain and excess energy, which can change behavior.

Cold nights, frost, drought, and other stressful growing conditions can cause grass to retain higher sugar levels. Pasture access should be introduced gradually, particularly when horses transition from winter hay or return to grazing after an extended period off grass.

In some horses, high-sugar pasture grass may be associated with excitability, restlessness, or increased reactivity. These changes may reflect rapid energy fluctuations, digestive discomfort or both. Fructans and other carbohydrates fermented in the hindgut can alter microbial populations and increase acidity, potentially contributing to gas, mild colic or inflammation.

Horses with insulin resistance or a history of laminitis may also become uncomfortable before more obvious clinical signs appear, so sudden behavioral changes on pasture should not automatically be dismissed as excess energy.

However, running, bucking, or playing after turnout also does not necessarily mean that grass sugar changed the horse’s emotional state. The excitement of turnout, social interaction, cooler weather, or a change in routine may also explain the behavior.

Alfalfa: Does it Make Horses Hot or More Energetic?

Alfalfa is commonly blamed for making horses “hot” because it contains more protein than most grass hay.

However, protein itself has not been shown to cause hyperactivity. Sugar, starch, and excess calorie intake are more likely to influence excitable behavior.

Alfalfa is often lower in sugar and starch than cool-season grass hay, but it is also more calorie-dense, and its flakes may weigh more. Replacing two flakes of grass hay with two flakes of alfalfa, for example, could therefore provide more forage by weight and more total energy.

This may benefit hard keepers or horses with greater calorie demands, but a horse already maintaining a healthy weight or lower workload may change behavior due to the additional energy.

Alfalfa’s higher protein content is generally not harmful to healthy horses, and excess protein is broken down and excreted in urine. This may increase water intake and urine production, resulting in wetter stalls and greater ammonia buildup if bedding is not managed properly.

Alfalfa is neither inherently good nor bad. Its suitability depends on the horse’s age, workload, body condition, health, and complete diet. Because nutrient content and flake weight vary, weighing the hay and obtaining a laboratory forage analysis are the best ways to determine exactly how much protein, sugar, starch, and minerals it provides.

How to Feed Horses for Balanced Emotional Health and Behavior

A well-designed feeding program supports physical comfort and steadier energy, but also takes into consideration the horse's individual lifestyle and needs.

Begin With Forage

Forage should form the foundation of the equine diet, and ideally be fed free-choice. Consistent access to hay or pasture grass supports normal digestive function and allows the horse to have natural foraging behavior.

Long periods without forage may contribute to gastric discomfort, stress, and unwanted behaviors.

Match Feed Type to Workload

Consider the horse’s current body condition, metabolism, and actual exercise when matching calorie intake. Many horses in light work need fewer calories than owners expect.

An easy keeper may receive adequate calories from forage and need only a ration balancer to supply essential vitamins, minerals, and amino acids. A hard keeper or performance horse may require a full-intake feed that provides additional calories and nutrients. Matching the type of full-intake feed to the horse’s forage type, workload, body condition, and individual needs further ensures the right balance of energy and nutrition.

Consider Fiber and Fat for Additional Calories and Energy

When a horse needs more calories but becomes reactive on higher-starch and sugar grains, feeds that derive more energy from fiber and fat ingredients may be more appropriate.

Ingredients such as beet pulp and soybean hulls provide highly digestible fiber. At the same time, vegetable oils and other fat sources increase calorie density without producing the same blood glucose response as a large starch meal.

Feed Smaller, More Frequent Meals

The horse’s stomach is designed for more frequent, smaller meals. Divide the daily grain concentrate over several meals and feed multiple times daily.

Avoid giving an oversized meal because smaller portions reduce the amount of starch entering the digestive tract at one time and help support more consistent nutrient delivery.

Make Dietary Changes Gradually

Sudden changes in hay, pasture, or concentrate can disrupt hindgut microbes and increase the risk of digestive upset or ulcers. Introduce new feeds gradually so the horse's digestive system has time to adjust.

Investigating Sudden Behavior Changes

Sudden changes in behavior can be associated with not only what the horse is fed but also anything from pain, gastric ulcers, dental conditions, lameness, poor saddle fit, hormonal concerns, insufficient turnout, to an unsuitable training program.

Consult a veterinarian when behavior changes are significant, persistent, or accompanied by weight loss, appetite changes, poor performance, sensitivity during grooming, or other signs of discomfort.

How Tribute Superior Equine Nutrition Supports Balanced Energy and Behavior

Tribute Superior Equine Nutrition offers full intake, fixed-formula feeds and ration balancers designed for different calorie needs, workloads, life stages, and the type of forage the horse is fed.

Choosing a feed that matches the horse’s actual requirements can help support digestive comfort, steadier energy and behavioral response to work and daily routines.

  • Essential K®: A low-NSC ration balancer that provides essential amino acids, vitamins and minerals without adding excess calories. It can be a good option for easy keepers, horses maintained primarily on forage, and horses that need concentrated nutrition without additional energy.
  • Kalm ‘N EZ®: A low-sugar and starch feed that supplies steadier energy through fat and fiber. It can help support horses that need additional calories without relying heavily on starch-rich cereal grains.
  • Alfa Essentials®: A low-NSC ration balancer formulated for horses consuming diets that contain 50% or more alfalfa or other legumes. It provides balanced nutrients without adding unnecessary calories.
  • Synergize®: A high-fat, high-fiber feed designed for performance horses and hard keepers with greater calorie demands. It provides additional energy to support body condition and steady energy without high-starch ingredients.

Because horses can respond differently to various feeds, Tribute’s free, personalized feeding plans can help owners select an appropriate full-intake feed or ration balancer based on forage type, age, activity level, body condition and other individual nutritional needs.

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Article By:
Kimberly S. Brown
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