Will Soy Harm My Horse?
Soy has become a hot topic in equine nutrition, often surrounded by myths, social media hype, and misconceptions with little grounding in scientific fact. As a result, some horse owners are prematurely removing this powerful ingredient from their horse's diet, potentially creating unintended nutritional gaps.
The truth is, soy remains one of the most beneficial ingredients you can include in your horse's diet when used appropriately. While soy sensitivities can occur in a small percentage of horses (estimated at around 10%), they are not the norm. It does not cause systemic inflammation, worsen EPM, or affect Lyme disease progression based on current understanding. In fact, adding in soy based concentrates often results in a lot of improvement in horses with these conditions.
For most horses, soy offers a rich source of high-quality protein and essential amino acids, supporting everything from muscle development to overall health.
Nutritional Impact
Is Soy a Good Source of Protein for My Horse?
Yes, soy is an excellent source of protein for horses! Soybean meal, one of the most commonly used soy products, typically contains 40-48% protein, making it a highly concentrated and efficient protein source. Soybean hulls, while lower in protein at 9-11%, are an excellent source of carbohydrates, offering 85% digestible energy. This makes soy a versatile and valuable ingredient in many equine feeds, providing both protein and energy.
What Amino Acids Does Soy Provide, and How Do They Benefit My Horse?
Soy products, including soybean meal and hulls, supply 18 of the 21 essential amino acids your horse needs. Amino acids are the building blocks of protein and are crucial for your horse’s daily health and well-being.
Muscle Development: Amino acids help build and maintain strong, healthy muscles, which is vital for performance and recovery.
Healthy Coat, Mane, and Tail: Protein supports a shiny coat and robust hair growth.
Energy Source: While carbohydrates are the body’s primary energy source, proteins can be converted into energy when necessary.
Hidden Benefits: Amino acids are essential for a strong immune system, healthy brain and nerve function, and maintaining a balanced gut. These benefits often reduce the need for additional supplements.
How Does Soy Compare to Other Protein Sources Like Alfalfa or Flax?
Here’s how common feed ingredients stack up in protein content:
Soybeans: 40-48% crude protein
Alfalfa: 12-25% crude protein
Flax: 20-28% crude protein
Oats: 11-20% crude protein
Corn: 10.4% crude protein
Rice Bran: 10-15% crude protein
Wheat: 11% crude protein
Beet Pulp: 8-10% crude protein
Soybean meal provides 2-4 times more protein than many other common feed ingredients. This concentrated protein reduces the amount of concentrate needed to meet your horse’s dietary requirements, lowering feeding rates and production costs for feed mills.
Health and Sensitivities
Does Soy Cause Hormonal Imbalances in Horses?
No. Research has found no significant evidence that soy impacts hormones in horses when compared to placebos.
Are Soy-Based Feeds Safe for Metabolic or Laminitic Horses?
Yes! Soy is an excellent option for horses with metabolic disorders or laminitis. These horses often require diets with low non-structural carbohydrate (NSC) levels, typically 10-12% NSC. The low feeding rate of soybean meal keeps NSC levels low while meeting protein needs, making it a safe and effective choice.
Is Soy Bad for Horses With Lyme or EPM?
No scientific evidence suggests that soy negatively affects horses with Lyme disease or equine protozoal myeloencephalitis (EPM). Soy remains a safe protein source for these conditions.
Processing and Forms
What’s the Difference Between Soybean Meal, Soy Hulls, and Full-Fat Soy?
Soybean Meal: Made by crushing soybeans and removing the hulls and oil, this is the most concentrated protein form.
Soybean Hulls: The fibrous outer shell of the soybean, often used for its digestible fiber content.
Full-Fat Soy: Includes the natural oil, providing added energy. This form skips the oil extraction process.
Did You Know? The oil extraction process involves hexane, which is removed through heat and steam, leaving a safe and nutrient-rich product.
Is Non-GMO or Organic Soy Better for My Horse?
Studies show no nutritional advantage to non-GMO or organic soy over conventional soy. Organic soy is also 3-4 times more expensive, making it less accessible for most horse owners. GMO soybeans, on the other hand, meet the same safety and nutritional standards while being more cost-effective.
Digestive and Behavioral Impacts
Does Soy Make Horses More Excitable?
No. Soy is high in protein and low in carbohydrates, which are the body’s main energy source. Feeding soy will not make your horse excitable or "hot." Protein is often calming to horses.
Practical Applications
Should I Feed Soy-Based Feeds Differently to Mares, Geldings, or Stallions?
No. Studies show no need to adjust soy-based feed strictly based on the horse’s sex. However, nutritional needs should always be tailored to a horse’s age, workload, and reproductive status. Pregnant or lactating mares and breeding stallions will have higher nutritional requirements compared to mature horses at maintenance. If you have concerns, please discuss with a qualified professional.
Is Soy Oil a Good Option for Adding Calories to My Horse’s Diet?
Not really. Most oils, including soy oil, do not provide enough calories in quantities typically consumed by horses. For weight gain, consider high-calorie concentrates and/or increasing forage intake instead.
How Much Soy Is Too Much?
There is no established threshold for "too much soy," but feeding soy-based products at the recommended rates is safe. Please discuss your specific needs with a professional for best results.
Industry and Quality Concerns
Are There Concerns About Pesticides in Soy?
No. Studies have shown that pesticide residues in soy products are well below levels harmful to horses. The EPA sets strict safety standards, which are available for review on the USDA website.
Is Soy GMO?
Yes, soybeans are one of the 14 bioengineered foods recognized by the USDA. Twenty GMO soybean varieties have been developed for traits like herbicide tolerance, insect resistance, and higher yields. These GMOs are rigorously tested for safety.
How Can I Ensure the Soy in My Horse’s Feed Is High Quality?
Here are a few tips:
Buy From Reputable Brands: Trusted companies prioritize quality.
Look for Fixed Formulas: Ensures consistent ingredients in every bag.
Choose Ionophore-Free Mills: Reduces contamination risks.
Check Freshness: Inspect feed bags for expiration dates and quality.
Closing Thoughts
Soy must be carefully considered in the diet especially to maintain a good Omega 3/6 balance
More research is needed to investigate soy in horses
Soy remains a powerful and beneficial ingredient in equine nutrition.
Understanding its role and proper use can help ensure your horse receives optimal care and nutrition.
By Annie Emery, MS CRC CESMT CENA
Revolution Equine Nutrition
With Special Guest: Samantha Holcomb
Samantha Holcomb, from Southern Minnesota, has built a career blending hands-on experience with academic expertise in equine and agricultural management.
Her equine journey began with showing miniature horses before expanding to full-sized horses. Samantha earned degrees in Equine Science and Animal Science with a minor in Agriculture Business from the University of Minnesota Crookston, where she gained practical experience caring for 40 horses of various breeds and ages.
After graduating, Samantha applied her skills in the swine industry, quickly rising to manage a 3,000-head sow farm by age 22. She later transitioned to agriculture technology, working as a scale technician at a soybean processing plant.
In 2018, Samantha purchased her current horse, a 2005 APHA gelding. Her broad expertise enables her to provide exceptional care, ensuring her horse ages gracefully and stays in top condition.
With a strong background in animal science and agricultural management, Samantha is passionate about lifelong learning and dedicated to advancing animal care.
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