Diet & Horse Behavior by a Vet – 2025 Guide to Starch, Fat, and Behavioral Reactivity 🥕🐴
In this article
Diet & Horse Behavior by a Vet – 2025 Guide to Starch, Fat, and Behavioral Reactivity 🥕🐴
By Dr Duncan Houston, BVSc
Introduction
Equine behavior is influenced by a variety of factors—training, environment, exercise, and yes, nutrition. In 2025, we're gaining more clarity on how a horse’s diet can impact their mental state and behavior. A recent study from Virginia Tech offers evidence that high-starch diets may increase reactivity, while low-starch, fat-balanced diets contribute to calmer, more manageable horses. This supports the longstanding anecdotal belief that grain-heavy diets can make horses “hot.”
Study Overview 📚
- Conducted by Virginia Tech graduate researchers
- Used 20 riding horses from the university’s equitation and hunter/jumper program
- Split into five groups, each receiving a different starch-to-fat ratio
- Starch content ranged from 7.1% to 14.3%
- Duration: 21 days, with standardized care and riding across groups
- Instructors and riders were blinded to diet assignments
Behavioral Assessment Criteria 🔍
Behavior was evaluated both on the ground and under saddle:- Catching and haltering
- Leading and grooming responses
- Reaction to leg aids
- Relaxation and submission
- Overall reactivity and rideability
Key Results 🧪
- No change in body weight or condition – all diets were balanced for energy and nutrient needs
- Higher starch diets correlated with higher reactivity scores from both riders and instructors
- Low-starch horses improved in behavior over time
- High-starch horses became more difficult to manage during grooming and riding
Implications for Horse Owners & Trainers 🎯
- Supports the traditional belief that grain-heavy diets make horses “hot” or anxious
- Offers guidance for feeding nervous, spooky, or anxious horses
- Highlights importance of balancing calorie sources – not all energy is equal in effect
Why Starch Affects Behavior 🧠
- Starch is rapidly digested in the small intestine, leading to glucose spikes
- This may increase adrenaline and cortisol levels, heightening reactivity
- Rapid digestion may also influence gut microbiome changes and discomfort
High-Starch vs. Low-Starch Diet Examples 🥣
High-Starch (Reactive Behavior)
- Oats, sweet feed, corn-based grain mixes
- Pelleted concentrates high in starch & sugar
Low-Starch (Calmer Behavior)
- Beet pulp (no molasses)
- Chopped hay-based feeds
- High-fat supplements (e.g., rice bran, flax)
Feeding Strategies for a Calmer Horse 🧘♂️
1. Prioritize Forage
- Hay should make up at least 1.5–2% of body weight daily
- Choose low-NSC tested hay for sensitive horses
2. Feed Fat for Energy
- Fats provide slow-release calories without behavioral spikes
- Safe options: canola oil, stabilized rice bran, flax meal
3. Avoid Sugary Treats
- Limit use of molasses feeds, sugary snacks, and cookies
4. Support the Gut
- Probiotics and prebiotics can help reduce inflammation and support mood
Case Example: Nervous Jumper Mare
- 8-year-old warmblood mare had high anxiety under saddle
- Diet included 6 lbs/day of sweet feed + 1 lb rice bran
- Transitioned to high-fiber, low-starch hay pellet with 2 lbs/day flax
- Within 3 weeks, riders reported better focus and rideability
FAQs About Horse Diet & Behavior
Q: Does a low-starch diet fix all behavior issues?
A: Not always. But it can reduce the excitability or “hot” temperament linked to feeding practices.
Q: How fast can I expect a difference?
A: Changes may appear within 1–3 weeks as the body adapts to a new fuel source.
Q: Can diet help a spooky trail horse?
A: Yes! Diet is one of the first places to evaluate if your horse is unusually reactive or easily startled.
Conclusion
In 2025, we have even more evidence that “you are what you eat” applies to horses too. High-starch diets may provide energy—but they can also contribute to behavioral issues. Horses on low-starch, high-fat diets show improved relaxation and manageability. Always consult a veterinarian or equine nutritionist before making big dietary changes to ensure balance and safety.
Need help adjusting your horse’s diet for calmer behavior or better focus? Visit AskAVet.com or download our app 📱 to consult with Dr Duncan Houston for a customized nutrition plan. 🩺🐴
