Threonine

Pure Amino Acid Supplement

Threonine is an essential amino acid that supports gut health, immune function, and protein synthesis in horses. Supplementing with our pure threonine powder is beneficial for growing horses, performance horses and those requiring additional gut support.

Aids in mucin production to support a healthy gut lining
Maintains nutrient absorption and feed efficiency
Contributes to muscle growth and maintenance
Involved in collagen and elastin production

Weight

2.2 lb

200 servings

4.4 lb

400 servings

11 lb

1000 servings

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+ Active Ingredients

Threonine

Threonine is an essential amino acid and one of the primary limiting amino acids in equine diets, meaning it often limits the rate of protein synthesis when insufficiently supplied. It plays a key role in maintaining normal muscle development, immune function, and digestive health.

Within the gastrointestinal tract, threonine is a critical component of mucin glycoproteins that protect and maintain the gut lining. Adequate threonine intake supports gut integrity, particularly in horses consuming high-grain or low-quality forage diets, or those experiencing digestive stress.

Beyond its role in gut barrier function, threonine contributes to the synthesis of structural proteins, enzymes, and neurotransmitters. It works synergistically with lysine and methionine to optimize amino acid balance, supporting lean tissue development and recovery in growing, performance, or metabolically challenged horses.

References

Mok, C.L., and Urschel, K.L. Amino acid requirements in horses. Asian-Australas J Anim Sci. 2020.
Myrie, S.B., et al. Effect of common antinutritive factors and fibrous feedstuffs in pig diets on amino acid digestibilities with special emphasis on threonine. J Anim Sci. 2000.
Gonzalez, L.M., et al. Alterations in Intestinal Permeability: The Role of the “Leaky Gut” in Health and Disease. J Equine Vet Sci. 2017.

+ Nutrient Analysis

Threonine Supplement for Horses

Directions for Use:

Consult with a nutritionist or veterinarian prior to use.
Top dress once daily on feed or ration.

Body Weight	Scoops	Dose
< 200 kg	½ scoop	2.5 g
200 – 500 kg	1 scoop	5 g
> 500 kg	1 ½ scoops	7.5 g
1 scoop = 9 cc = 5 grams

Warning / Caution:

A scale should be used with all individual ingredients to ensure accurate dosing.

For Equine Use Only. Not for use in horses intended for food.
Keep out of reach of children.

Active Ingredients: Per gram serving
Ingredient	Per 5 g
L-Threonine	5	g

Recommended Use: Supports protein synthesis, gut health and immune system function.

Packaged by: Mad Barn Inc., Petersburg, ON, N0B 2H0, Canada.

Disclaimer: These statements have not been evaluated by Health Canada or the FDA. This product is not intended to diagnose, treat, cure or prevent any disease.

1 kg (2.2 lb): SKU 628055182191

+ Feed Cost

Metric (kg)Imperial (lb)

Metric (kg)

Imperial (lb)

Body Weight:		kg
Serving size:		grams
		scoops

* Recommended serving size of 1 grams per 100 kg (220 lb) of body weight

5% Subscription Discount

	Servings	Cost Per Day

Disclaimer: Recommended feeding rate varies depending on your horse's condition and current diet. Consult with a nutritionist to determine the appropriate inclusion rate for your horse.

+ Questions (18)

Frequently Asked Questions

What is Threonine used for in horses?

Threonine is an essential amino acid used by the horse’s body to build proteins. It plays a role in muscle development, tissue repair, immune function, and digestive health. Because horses cannot synthesize this amino acid, it must be supplied through the diet. Supplementation helps ensure that protein already present in the diet can be effectively utilized for growth, conditioning, and recovery.

What are the signs of Threonine deficiency in horses?

Possible signs of inadequate Threonine intake include difficulty building or maintaining topline, poor muscle tone, slower recovery after exercise, reduced growth in young horses, and a dull hair coat. Because these issues can also be linked to other nutrient imbalances, it is best to evaluate the full diet with a nutritionist before supplementing with single ingredients.

What is the correct ratio of Lysine, Methionine, and Threonine in the equine diet?

Lysine, Methionine, and Threonine are considered the three most limiting amino acids in the horse’s diet. While exact requirements vary, research suggests that a practical ratio for growing and working horses is approximately 5:3:2 for Lysine, Methionine, and Threonine. Balancing these amino acids helps maximize protein utilization and supports muscle and tissue development.

What are the best sources of Threonine for horses?

Threonine is naturally found in protein-rich feeds such as soybean meal, canola meal, and legume forages like alfalfa. However, levels can be low in grass hays and cereal grains, which are common components of equine diets. In these cases, pure Threonine supplements may be used to ensure adequate intake and balanced amino acid profiles.

Which horses benefit the most from Threonine supplementation?

Horses that may benefit most from Threonine supplementation include those fed low-protein or poor-quality forage, performance horses with higher demands for muscle recovery, broodmares, and growing horses. Senior horses with reduced digestive efficiency may also benefit from targeted amino acid support to maintain condition and topline.

Why is Threonine considered a limiting amino acid for horses?

Threonine is considered a limiting amino acid because it is often present in lower amounts relative to the horse’s requirements. When an amino acid is limiting, it restricts the body’s ability to fully utilize other amino acids for protein synthesis. In many equine diets, Threonine is the next most commonly deficient amino acid after Lysine and Methionine. Ensuring adequate Threonine intake helps maximize protein utilization and supports muscle development, growth, and tissue repair.

Will Threonine help my horse gain weight and improve topline?

Threonine plays a key role in muscle health, topline, and condition by providing one of the most limiting amino acids for protein synthesis. Horses consuming low-protein or poor-quality forage may struggle to build or maintain muscle even with sufficient calories. Supplementing with Threonine helps ensure that existing calories in the diet can be effectively used for topline development and muscle repair. Threonine is not a weight-gain supplement. Weight gain requires additional calories from forage, fat, or grains. However, when calorie needs are already met, supplementing Threonine can help improve condition by preventing amino acid deficiencies that limit muscle growth. The best results are seen when pairing a balanced diet with an appropriate exercise program.

Should Threonine be supplemented with other amino acids in horses?

Whether Threonine should be supplemented on its own or with other amino acids depends on the horse’s diet. For best results, it is usually recommended to supplement Lysine, Methionine, and Threonine together, since these three are the most commonly limiting amino acids in equine diets. Providing them in combination, such as with Mad Barn’s Three Amigos product, helps ensure that protein synthesis is properly supported and that the diet is balanced for muscle development and recovery.

Is Threonine safe for broodmares and growing horses?

Yes. Threonine is an essential amino acid and is safe for broodmares and young, growing horses, who have higher requirements. As a building block of protein, it supports foal development during pregnancy, milk production during lactation, and proper muscle and tissue growth in young horses. This supplement provides pure Threonine with no fillers or additives and should be fed as part of a balanced diet.

Is Threonine safe for horses with Cushing’s (PPID), insulin resistance (IR), or other metabolic issues?

Yes. Threonine is safe for horses with metabolic conditions. This supplement contains only the amino acid Threonine and contributes no sugar, starch, or fillers, making it suitable for restricted diets. This product has 0% NSC content and can be fed safely to horses with PPID, IR, EMS, or laminitis.

Is Threonine competition-legal for horses?

Yes. Threonine is competition-legal and does not contain prohibited substances based on current FEI rules. Regulations may change, so always confirm with your sport’s governing organization.

Is Threonine safe to use in horses taking medications?

Yes. Threonine can be used safely alongside common equine medications, including NSAIDs and PPID therapies. There are no known drug interactions.

Can the daily dose of threonine be split between meals?

Yes. The daily dose can be split into two meals or fed at once. Splitting may help with acceptance in picky horses, but it is not required.

Does Mad Barn’s Threonine supplement come with a scoop?

Yes. Each container includes a 5 g scoop for convenient daily feeding. To ensure accurate dosing, it is recommended to weigh the powder with a scale.

Can Threonine be fed with Omneity, AminoTrace+, or other vitamin/mineral supplements?

Yes. Threonine can be combined with Omneity or other vitamin and mineral supplements. Omneity already provides balanced vitamins and minerals, but additional amino acid support may be beneficial when lower-quality forages are being fed. Threonine supplementation is often not required with AminoTrace+, since it already contains elevated amino acid levels, but it can be added if extra support is needed.

Can Threonine be fed with Visceral+, Optimum Probiotic, or other gut health supplements?

Yes. Threonine is compatible with Visceral+, Optimum Probiotic, and other gut health products. As a pure amino acid, it does not interfere with digestive support supplements.

Is Threonine a powder or a pellet, and how should it be fed to horses?

Threonine is a powdered supplement that can be top-dressed on feed or mixed into soaked hay cubes, beet pulp, grains, or a mash. It can be fed dry or soaked depending on your horse’s routine.

What is the shelf life of Threonine and how should it be stored?

Threonine has a guaranteed shelf life of two years from the date of manufacture, printed on the label. Store in a cool, dry place with the container tightly sealed to maintain freshness and potency.

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Have a question about this product? Ask below and our nutritionists will be happy to assist.

Essential Amino Acid for Horses

Pure L-threonine for protein synthesis and gut health.

Mad Barn's Threonine is a 99% pure crystalline L-threonine powder used to improve the balance of limiting amino acids and support optimal protein quality in the diet.

Threonine is an essential amino acid used to build proteins and produce mucin, a major component of the protective mucus lining in the digestive tract.

Provides pure L-threonine with no fillers or additives
Improves dietary supply of limiting amino acids
Supports muscle growth and maintenance in horses
Promotes mucin production and intestinal integrity

Why Horses Need Threonine

Your horse can get enough protein and still lack essential amino acids.

If your horse struggles to build muscle or maintain a healthy topline, feeding more protein isn't always the answer. Horses need the right balance of essential amino acids to build muscle, repair tissues, and support normal growth and recovery.

Threonine is one of the main limiting amino acids in equine diets, along with lysine and methionine. When any of these amino acids is deficient, protein synthesis will be limited, even if the diet supplies adequate crude protein.

Supplementing L-threonine helps correct amino acid imbalances, allowing your horse to make better use of the protein in their forage and feed. By preventing a threonine deficiency from restricting protein synthesis, it supports normal muscle development, topline maintenance, and tissue renewal.

Threonine also plays an important role in digestive health in horses. It is required to synthesize mucins, proteins that form the protective mucus barrier lining the gastrointestinal tract. Horses prone to gastric sensitivity benefit from supplemental threonine to maintain normal intestinal barrier function and gut comfort.

99%

Pure L-Threonine

Contains crystalline L-threonine without added sugars, starches, sweeteners or fillers.

Essential

Amino Acid

Threonine must be supplied in the equine diet and is required for normal protein synthesis.

5 g

Serving Size

One scoop per day provides 5 g of threonine powder for a 500 kg (1,100 lb) horse and is easy to top-dress onto feed.

$0.16

Cost Per Day

Affordable pure amino acid supplement, with a 1 kg (2.2 lb) container lasting 200 days at the typical serving.

Which Horses Benefit Most from Threonine?

Growing horses, lactating mares, and horses in exercise training have higher protein and amino acid requirements to support physiological needs. Horses fed mature grass hay or diets with low protein quality are also at risk of inadequate amino acid intake, even when overall crude protein levels are sufficient.

Signs of inadequate protein or amino acid intake can include poor condition, muscle loss, slow hoof growth, poor coat quality, reduced stamina, and low milk production in lactating mares. Threonine also supports intestinal barrier function, making adequate intake important for horses prone to digestive issues.

Horses with poor topline

When calories and exercise are adequate, insufficient essential amino acids can limit muscle protein synthesis and make it difficult to build or maintain topline.

Performance horses

Training increases protein turnover, so horses need more amino acids to maintain muscle tissue and support recovery after exercise.

Growing horses

Young horses have elevated requirements for essential amino acids to support the rapid synthesis of muscle and other developing tissues.

Forage-based diets

Diets consisting primarily of mature grass hay or lower-quality forage may provide adequate crude protein while still being poorly balanced in limiting amino acids.

Horses needing gut support

Threonine is required to synthesize mucin proteins that form the protective mucus layer lining the gastrointestinal tract.

Broodmares

Pregnancy and lactation increase amino acid requirements to support fetal growth, maternal tissues and milk protein production.

Senior horses

Aging horses losing muscle mass may need additional essential amino acids to support muscle maintenance, especially if dental problems or digestive changes limit nutrient availability.

Horses under stress

Horses experiencing stress from travel, competition, or changes in routine need adequate threonine intake to support antibody production and normal immune function.

Recovering horses

Horses recovering from illness, injury, or surgery may need additional amino acids to support tissue repair and normal recovery.

Threonine Requirements

How much threonine does a horse need?

Horses cannot make threonine on their own, so they must obtain it from their diet. The National Research Council (NRC) provides scientific guidelines for how much of each nutrient horses need to maintain normal health. Based on these guidelines, a typical 500 kg (1,100 lb) adult horse at maintenance needs approximately 17 grams of threonine per day.

This requirement is calculated as 62% of the lysine requirement, or approximately 2.7% of dietary crude protein intake. These figures represent the total threonine needed from the diet, not the amount that must be supplemented.

17 g

Maintenance

Estimated threonine requirement per day for a 500 kg (1,100 lb) adult horse at maintenance.

19 – 23 g

Exercise

Estimated requirement per day for a 500 kg (1,100 lb) horse in light to heavy work.

18 g

Weanlings

Estimated daily requirement for a 170 kg (370 lb) weanling between 4 – 10 months of age.

29 g

Yearlings

Estimated daily requirement for growing yearlings between 11 – 17 months of age.

Threonine requirements vary between horses. Individual needs depend on age, body weight, activity level, and physiological status, including growth, pregnancy, and lactation. To determine your horse's threonine requirements and whether supplementation is needed, submit your horse's diet for a free evaluation by a Mad Barn equine nutritionist.

How Threonine Works

Threonine is a key building block of proteins.

The horse's body continuously breaks down and replaces proteins in muscle and other tissues. To produce new proteins, cells assemble amino acids in specific sequences through a process called protein synthesis.

Threonine is one of the essential amino acids required to make muscle proteins that support growth and tissue repair, enzymes that regulate metabolism, and antibodies involved in immune defense. It is also particularly abundant in mucins, the glycoproteins that form the protective mucus barrier lining the gastrointestinal tract.

Protein formation

Threonine supplies one of the essential amino acids needed to produce muscle proteins, enzymes, antibodies and other functional proteins.

Muscle development

Muscle cells build new proteins, including actin and myosin, by linking amino acids together in precise sequences. Threonine must be available for incorporation at specific positions in these proteins, so insufficient threonine can limit their production.

Mucus production

Threonine is required to produce mucins, proteins with attached sugar chains that form a protective mucus layer over intestinal cells. This layer lubricates the digestive tract and limits direct contact between intestinal cells, microbes, and digestive contents.

Antibody production

Threonine is used by immune cells to produce antibodies, including immunoglobulin A (IgA). IgA is secreted into the intestinal mucus, where it binds microbes and helps prevent them from attaching to the gut lining.

More crude protein is not always the answer. When dietary protein quality is inadequate, protein synthesis is restricted by the first limiting amino acid. Adding more crude protein from poorly balanced sources may not correct this deficiency. Instead, excess amino acids are broken down, and their nitrogen is excreted as urea.

Threonine for Gut Health

Essential for protecting the gastrointestinal tract

The intestinal barrier is essential for nutrient absorption and immune protection in horses. Epithelial cells lining the intestine absorb digested nutrients, while tight junctions between these cells regulate the movement of substances across the gut wall. A protective mucus layer covers this surface, limiting contact between intestinal cells and bacteria, microbial toxins, and other potentially harmful substances.

When this barrier is damaged by inflammation, reduced blood flow, or certain medications, intestinal permeability can increase. Bacteria and microbial toxins can cross the intestinal wall, activating immune responses and contributing to inflammation. Damage to the intestinal epithelium can also interfere with nutrient absorption and fluid balance. These disruptions are associated with colitis, intestinal ulceration, and other conditions that compromise mucosal integrity.

The protective mucus layer contains high concentrations of mucin glycoproteins, which are continuously synthesized and secreted by specialized intestinal cells called goblet cells. Threonine is abundant in mucins and provides attachment sites for carbohydrate chains that give mucins their hydrated, gel-like structure. This creates substantial demand for threonine in the diet.

Studies in other species have found that intestinal tissues can use between 60 – 90% of threonine supplied by the diet, although this range has not been established in horses. When threonine intake is inadequate, the demand for mucin synthesis can compete with protein synthesis in muscle and other tissues. In neonatal piglets, severe threonine deficiency reduced intestinal mucin content and affected the mucus-producing cells of the gut.

Best Amino Acid Supplements

Does your horse need L-threonine or a blend of amino acids?

Pure Threonine is most appropriate when you are correcting a known or suspected threonine deficiency in an otherwise balanced ration.

If your horse needs limiting amino acid support for topline, muscle development, growth or performance, supplementing lysine, methionine and threonine together is usually a better choice.

Precision Formulation

Pure Threonine

Best when you specifically need to increase threonine in an otherwise balanced amino acid program.

Your horse's ration has been evaluated for amino acid content
Lysine and methionine are already adequately supplied in the diet
You need to increase threonine independently of other nutrients
A nutritionist has recommended additional threonine

Best for Most Horses

Mad Barn Three Amigos amino acid supplement for horses

Amino Acid Blend

For most horses, Mad Barn's Three Amigos is the better choice because it supplies lysine, methionine and threonine together in an optimal 5:3:2 ratio.

Horses struggling to build or maintain muscle and topline
Growing horses and lactating mares with higher amino acid requirements
Performance horses with increased demands for muscle maintenance and recovery
Horses consuming forage-based diets with lower protein quality

How to Feed

How to Feed Threonine

Feed 1 Scoop Per Day

For horses weighing 200 – 500 kg (440 – 1,100 lb), add 5 grams to their regular ration.

Ensure Adequate Crude Protein

The complete diet must provide enough total protein for your horse's age and workload.

Balance Other Amino Acids

Ensure intake of lysine, methionine, and other essential amino acids also meets your horse’s requirements.

Not sure how much threonine your horse needs? Our nutritionists can evaluate your horse's diet and calculate their nutritional requirements to recommend the correct feeding rate. Submit your horse's diet online for a free analysis.

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Expert support

Need help deciding? Talk to a nutritionist for free before you buy.

Every horse is different, including their forage, turnout, workload, body condition, age, supplement regimen, protein and amino acid intake, and health history. Always consult a qualified nutritionist or veterinarian before changing the feeding program, especially when inadequate protein or amino acid intake is suspected.

Submit your horse's diet for analysis online.

One of our equine nutritionists will be happy to provide a complimentary review and help determine whether Threonine or Three Amigos is the best fit.

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Threonine

References

Pure L-threonine for protein synthesis and gut health.

Your horse can get enough protein and still lack essential amino acids.

Which Horses Benefit Most from Threonine?

Horses with poor topline

Performance horses

Growing horses

Forage-based diets

Horses needing gut support

Broodmares

Senior horses

Horses under stress

Recovering horses

How much threonine does a horse need?

Threonine is a key building block of proteins.

Protein formation

Muscle development

Mucus production

Antibody production

Essential for protecting the gastrointestinal tract

Does your horse need L-threonine or a blend of amino acids?

Pure Threonine

Amino Acid Blend

How to Feed Threonine

Feed 1 Scoop Per Day

Ensure Adequate Crude Protein

Balance Other Amino Acids

Try Threonine Risk-Free

Need help deciding? Talk to a nutritionist for free before you buy.

Submit your horse's diet for analysis online.

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Threonine

References

Pure L-threonine for protein synthesis and gut health.

Your horse can get enough protein and still lack essential amino acids.

Which Horses Benefit Most from Threonine?

Horses with poor topline

Performance horses

Growing horses

Forage-based diets

Horses needing gut support

Broodmares

Senior horses

Horses under stress

Recovering horses

How much threonine does a horse need?

Threonine is a key building block of proteins.

Protein formation

Muscle development

Mucus production

Antibody production

Essential for protecting the gastrointestinal tract

Does your horse need L-threonine or a blend of amino acids?

Pure Threonine

Amino Acid Blend

How to Feed Threonine

Feed 1 Scoop Per Day

Ensure Adequate Crude Protein

Balance Other Amino Acids

Try Threonine Risk-Free

Need help deciding? Talk to a nutritionist for free before you buy.

Submit your horse's diet for analysis online.

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