Feeding Alfalfa to Horses: Pros & Cons of this Forage in the Diet

Alfalfa is a popular forage choice for horses and an ingredient in many equine feeds. This legume forage can be processed and preserved in many different ways to make it easier to incorporate into the diet.

Alfalfa is nutrient-dense and is an excellent source of energy, protein and minerals in the equine diet. It is also typically low in non-structural carbohydrate content.

This makes it a valuable roughage to include in the diets of pregnant and lactating mares, mature performance horses, or other horses requiring protein supplementation.

However, some horse owners hesitate to feed alfalfa due to concerns about its safety. If you are considering adding alfalfa to your horse’s diet, and want to know if it is a good choice, then this article is for you.

Alfalfa for Horses

Alfalfa (Medicago sativa) or lucerne is a perennial legume plant that is grown as a high-yield forage crop around the world.

Alfalfa originates from the Mediterranean and southwest Asia. It has since been developed into various cultivars that can withstand a range of growing conditions.

Due to its deep root structure, alfalfa is known to be drought tolerant and grows best in well-drained, loamy soil.

Optimal growing conditions are average day temperatures of 25^oC (77^oF), 600 – 1200 mm annual rainfall and soil pH of 6.5 – 7.5. ^[1]

Alfalfa is a high-yielding forage crop that can produce up to 27 tons of dry matter per hectare with a higher protein yield than soybeans. ^[1]

It can be seeded for pasture grazing but requires rotational grazing strategies because it is less tolerant to intensive grazing than grasses such as timothy or teff.

Nutritional Composition of Alfalfa

Alfalfa is known as the “Queen of Forages” because of its high protein and energy content, making it an important protein source for the livestock industry. ^[1]

Below are averages and reported ranges of nutritional profiles over 200,000 legume hay samples analyzed by Equi-Analytical from 2004 – 2022: ^[2]

• Crude Protein: 21% (18 – 24%)
• Acid Detergent Fibre: 30.5% (27 – 34%)
• Neutral Detergent Fibre: 38.5% (33.5 – 43.5%)
• Water-soluble carbohydrates: 8.8% (6.8 – 10.8%)
• Ethanol-soluble carbohydrates: 6.8% (5.2 – 8.4%)
• Starch: 1.3% (0.5 – 2.15%)

Grass hays such as timothy, teff, orchard grass, or brome tend to be lower in protein and higher in neutral detergent fibre (NDF) than alfalfa hay. The hydrolyzable carbohydrate component of NSC (starch and sugar) is also higher in grass hay.

Variation

Nutritional values vary depending on growing conditions, soil nutrient levels and harvesting conditions. The only way to know the composition of the alfalfa hay you are feeding to your horse is to submit a sample for analysis.

The major factors that influence the nutritional composition of alfalfa include: ^[1]

• Growth stage
• Cut number
• Leaf-to-stem ratio
• Moisture conditions
• Processing methods

Maturity

As the plant matures, the protein content decreases and can become bound by lignin making it unavailable. The fibre (NDF and ADF) content increases with maturity. The protein content is densest in the leaves, whereas the stems are high in fibre.

The leaf-to-stem ratio is higher in earlier growth stages; at this stage, the stems are lower in fibre. The leaves are less abundant at later growth stages, and the stem becomes more rigid due to higher fibre and lignin content.

The nutritional content of alfalfa at different growth stages is: ^[1][3]

Alfalfa should be harvested between the late vegetative and early flowering stages to obtain the most nutritionally-dense and palatable hay while supporting plant regrowth.

Harvesting

Alfalfa is a high-yielding crop that can be cut several times through the growing season. In North America, three or four cuts of alfalfa hay are typically achieved in one season.

The first cut often contains weeds and other grasses, and the alfalfa may have a high stem content. Depending on growing conditions, the second cut may have a lower leaf-to-stem ratio than later cuts. ^[4]

Moisture Content

The handling of alfalfa after cutting can significantly impact its nutritional profile. Baling at a lower moisture content increases the loss of leaves and therefore reduces the protein content.

In contrast, baling at a higher moisture level maintains a higher nutritional value but increases the risk of mold growth and may require applying preservatives. ^[5]

Processing methods, such as raking during hay curing, can also affect leaf loss and nutritional value. ^[6]

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Forms of Alfalfa for Horses

As a feed for horses, alfalfa can come in many shapes and sizes, from pasture to chopped hay to processed pellets. While most forms of alfalfa provide the same nutrients on a dry weight basis, some forms may have unique nutritional qualities.

Below are some of the characteristics of different forms of alfalfa.

Pasture:

Alfalfa pasture is generally higher in protein, hydrolyzable carbohydrates (HC) and energy content than grass pasture. ^[2] This makes it a good option for horses in heavy exercise, growing horses and lactating mares.

Alfalfa is also a palatable forage; horses often prefer it over grass. However, some research suggests that horses prefer clover over alfalfa pasture. ^[7]

Hay:

Alfalfa hay can be purchased alone or mixed with grass hay (i.e. Timothy/Alfalfa blends). Horses typically prefer alfalfa hay over grass hays, such as Bermuda or Brome hay. ^[8]

Alfalfa is easily digested and provides a good source of calories, protein, vitamins and minerals, making it ideal for horses that need a nutrient-dense diet. ^[9]

The hay is also rich in digestible fibre, which supports hindgut health and microbial fermentation. Microbes in the horse’s hindgut convert the fibre into volatile fatty acids, which are an excellent source of energy for horses. ^[10]

Haylage:

Alfalfa haylage is a fermented form of alfalfa that is commonly fed to dairy cattle. It provides a higher nutrient density when compared to alfalfa hay, but it must be processed and preserved properly so that mold and bacterial toxins do not form.

Haylage and silage are commonly fed to horses in Europe and other parts of the world, where frequent rainfall makes it hard to dry properly and bale hay.

Chop:

Chopped alfalfa, also called green chop alfalfa, is cut and fed immediately before it has dried. This form of alfalfa is commonly fed to dairy cattle.

Green chop alfalfa has a nutritive value similar to alfalfa pasture, although its energy and protein content can vary depending on the plant’s maturity stage at the time of harvesting.

Chopped alfalfa can also be fed after it has dried, although the nutrient density is lower due to leaf fracture and loss.

Cubes and Pellets:

Alfalfa cubes and pellets are made from dried, compressed alfalfa hay. They can also be sold in a mix with other forages.

The pellets typically have a smaller particle size than alfalfa cubes. Both typically have a nutrient profile similar to alfalfa hay and are digested similarly. ^[11]

Both cubes and pellets are a good option for underweight horses and horses with dental issues, as they can be soaked to form a mash that does not require extensive chewing. This allows for nutrient-dense meal that can be eaten relatively quickly.

Caution must be taken when feeding dry cubes and pellets as these increase the risk of choke because they can be consumed very quickly with minimal chewing required. ^[13]

Cubes and pellets are also less dusty than hay and result in lower feed waste. However, diets that have much of the long-stem hay replaced by cubes or pellets can affect natural foraging behaviours and may increase stereotypical behaviours such as cribbing. ^[13]

Benefits of Alfalfa for Horses

Alfalfa is a nutritious forage that can benefit many classes of horses, including those with elevated energy, protein, or vitamin and mineral requirements.

Due to its high energy, protein, and calcium content, alfalfa must be carefully added to the diet to avoid dietary imbalances.

Growing Horses

Growing horses require a carefully balanced diet to support healthy development. Alfalfa is a good forage source to meet young horses’ digestible energy and protein needs.

However, feeding alfalfa hay on its own may provide too much digestible energy, which can lead to a fast growth rate and increase the risk of developmental orthopedic disease. ^[14]

Alfalfa is also a good source of calcium, needed for bone growth. However, the ration must be balanced to provide an appropriate ratio of calcium and phosphorus with adequate quantities of both minerals to support proper bone development. The calcium to phosphorus ratio should be 2:1 in diets for growing horses.

Lactating Horses

Mares in the early stages of lactation have some of the highest energy and protein requirements of any class of horse. It is important to feed lactating mares an adequate diet to ensure they produce enough good quality milk to support the health of their growing foal.

Alfalfa hay is a particularly good option for lactating mares because it is nutrient-dense. Additionally, the higher voluntary intake compared to other hays makes it a good option if a mare’s appetite is limiting her intake.

Horses with Ulcers

Because of its high protein and calcium content, alfalfa has been recognized as effective at buffering stomach acid. This can help increase the stomach’s pH and reduce the risk of gastric ulcers. However, not all studies show this benefit so more research is needed.

Gastric ulcers occur when stomach acid causes painful lesions or sores to form on the lining of the horse’s stomach. Ulcers are particularly prevalent in performance horses, affecting up to 100% of Thoroughbred racehorses. ^[15]

Feeding alfalfa may also decrease the secretion of gastric acid from stomach cells. Research in rats shows that a high-calcium diet inhibits the production of stomach acid, resulting in a higher pH. ^[16]

In one study, diets containing alfalfa hay significantly decreased the number and severity of gastric lesions in horses. ^[16]

However, another study found no effect on gastric ulcers in foals fed either alfalfa chaff or pellets at weaning. ^[36]. These foals were also fed 2.7 kg (6 lb) of oats per day which may have had enough hydrolyzable carbohydrate (HC) content to negate the buffering effect of the protein and calcium in the alfalfa products.

Additionally, alfalfa can be a good option to meet caloric needs while avoiding excessive concentrate intake. Grain-based feeds can exacerbate ulcers due to high HC content. ^[17]

Performance Horses

Horses in moderate to heavy work have higher energy and protein needs than those at maintenance. Alfalfa can be used as a portion of the forage supply to meet these needs.

As previously mentioned, alfalfa can also benefit exercising horses at higher risk of gastric ulcers by helping buffer gastric acids. ^[15]

Keep these considerations in mind when adding alfalfa hay to the diet of an exercising horse: ^[18]

• Heat production: Protein generates more heat during digestion than fat. The high protein content of alfalfa may negatively impact performance by increasing body temperature.
• Hydration status: Excess protein consumption increases the need to eliminate nitrogen via urine which removes water from the body and can impact hydration during exercise.
• Electrolyte balance: The high calcium content can disrupt electrolyte balance during and after exercise.

These factors have less of an impact on horses performing short bursts of intense exercise (i.e. racehorses) and are more of an issue for horses performing prolonged exercise (i.e. endurance racing).

It is generally not recommended to feed a high level of alfalfa (more than 30% of forage) to endurance horses, especially in hot conditions. ^[18]

Common Concerns with Alfalfa

Some horse owners express concerns about feeding alfalfa to their horses because they worry about contributing to hot behavior, effects on the calcium-to-phosphorus ratio of the diet, and whether alfalfa causes enterolith formation.

Some of these concerns are not supported by research, while others can be managed by properly balancing the diet with the inclusion of alfalfa.

Hydrolyzable Carbohydrates

Hydrolysable carbohydrate (HC) is the carbohydrates that are digestible in the small intestine of horses and can stimulate insulin release. In equine nutrition, it is better to refer to HC than the commonly reported non-structural carbohydrate (NSC) which also includes fructans – a carbohydrate that does not affect insulin levels.

Alfalfa has developed a reputation as a forage that is not appropriate for metabolic horses. Some horse owners believe it should not be fed to horses with Equine Metabolic Syndrome because of the starch and sugar content.

However, the higher energy content of alfalfa compared to grass hay does not come from the hydrolyzable carbohydrates.

Several studies have compared alfalfa hay with other hays such as Orchard, teff, wheat, and oat. In general, the HC content of alfalfa is lower than grass or cereal hays. ^[19][20][21]

However, for reasons that are not clear, some metabolic horses do become footsore on alfalfa. It may be the high protein that triggers an insulin response since it is known to have a low glycemic index. This requires further study but if you are intending to feed alfalfa to a metabolic horse introduce it slowly and carefully.

Rather than using the plant species to estimate HC content, consider that 0ther factors such as drought, cold stress, the stage of maturity and the time of day when the hay is cut have a greater impact on the HC content of the hay. ^[22]

It is always recommended to submit your hay for forage analysis to determine the HC content.

Behavioural Reactivity

Whether or not alfalfa causes more reactive behaviour than other types of forage has not been studied closely in horses.

However, feeding an alfalfa-based meal in place of grain may reduce the incidence of stereotypies such as cribbing. ^[23] Other components of the diet fed in combination with alfalfa may impact the frequency of stereotypic behaviours. ^[24]

A properly balanced diet that includes alfalfa has not been shown to increase reactivity.

Calcium to Phosphorus Ratio

Alfalfa is higher in calcium relative to phosphorus content, leading to a high calcium-to-phosphorus ratio if the diet is not properly balanced.

The ideal calcium to phosphorus ratio is between 1.2:1 and 2:1.

Horses may tolerate a calcium to phosphorus ratio up to 6:1 without outward signs of a problem. However, Whitlock et al fed diets with either a ratio of 1.16:1 or 4.12:1 and found a high proportion of lamellar bone than osteonic bone in the horses fed the high calcium diet. ^[38] Lamellar bone is the dead, organized outer layer of bone while osteonic bone is capable of growth, healing and remodeling in response to stresses.

If you are feeding alfalfa, you may need to reduce other sources of calcium in the diet or add phosphorus sources to ensure the calcium-to-phosphorus ratio remains within advisable limits. Feeds such as beet pulp are low in phosphorus and high in calcium and therefore may need to be reduced when feeding a high amount of alfalfa.

Feeds such as wheat bran or distillers grains and supplements such as monosodium phosphate can be used to increase phosphorus intake and balance the diet.

Urinary Stones

High calcium diets could put horses at higher risk of urinary stones. Horses do not regulate their intestinal absorption of calcium, therefore higher calcium in the diet will mean more is absorbed. They will excrete the excess calcium in urine which is what makes urine look cloudy.

Calcium precipitates out in alkaline urine of horses, as calcium carbonate. This can lead to accumulation of stones or sludge along the urinary tract and potentially blocks the flow of urine. This is most common in geldings because their urethra is tortuous compared to a mare and not as large in diameter as a stallion. ^[39]

Any sex can develop stones in the kidney or bladder.

Enteroliths

High proportions of alfalfa in the diet (greater than 50 – 70% of dry matter) are associated with a risk of enterolith formation. Enteroliths are mineral-based stones that form in the intestines when a horse consumes an indigestible foreign object such as sand.

Horses fed high-alfalfa diets have higher colonic mineral concentrations and lower colonic pH, which may explain the heightened risk of enteroliths.

However, most horses fed a high alfalfa diet do not develop enteroliths, so the higher risk may not be due to alfalfa consumption alone. ^[25] Additional factors such as a lack of pasture access and excessive mineral intake could lead to enterolith formation. ^[25][26][27] Some breeds, such as Arabians and Arabian crosses, may be more prone to developing enteroliths. ^[25]

If your horse needs alfalfa in their diet, a properly balanced feeding plan and good management practices to reduce sand or dirt ingestion can go a long way to preventing the development of enteroliths.

Hoof Sensitivity

Anecdotal reports suggest some laminitis-prone horses may be sensitive to alfalfa inclusion in the diet. Alfalfa intake appears to trigger laminitis episodes in susceptible horses. ^[28]

It is unclear why this occurs but could be due to excess protein intake from alfalfa hay. Elevated amino acids in the blood following alfalfa intake can stimulate insulin secretion, affecting laminitis risk. ^[29]

If your horse is prone to laminitis, it may be advisable to switch to grass hay if you notice increased hoof sensitivity when fed alfalfa.

Respiratory Irritation

Some horse owners express concerns that alfalfa hay makes their horse cough. ^[13]

However, it is not the alfalfa hay itself but rather the dust or mold content of any hay that can aggravate respiratory conditions such as heaves.

The dustiness of hay is related to the moisture content. Drier alfalfa hay will tend to be dustier as the leaves are more likely to shatter.

Alfalfa hay is generally baled at a higher moisture level (12 – 20 % moisture) than grass hays (8 – 15% moisture). This keeps a higher proportion of leaves intact, which ensures a high protein hay. This practice also reduces the dust from fine particles. However, if stored or handled incorrectly, the higher moisture content can lead to more mold and mycotoxins, which can irritate the respiratory tract. ^[30]

Regardless of the type of forage, always evaluate your hay for the presence of dust and mold. Dusty hay can be soaked or steamed to reduce respiratory irritants. Look out for brown or grey spots in the hay which can indicate mold and avoid feeding this hay.

Blister Beetles

Blister beetles are a pest commonly found in Midwestern states such as Kansas, Oklahoma and Colorado. They are attracted to blooming forages, such as alfalfa. These beetles produce a toxin called cantharidin which can be deadly for horses.

Horses that consume alfalfa contaminated with blister beetle fragments or oils from the beetle may show signs of gastrointestinal or urinary irritation, including: ^[31]

• Blisters on the tongue and mouth
• Colic and diarrhea
• Problems with urination or blood in the urine

Talk to your hay provider about the presence of blister beetles in their fields, especially if your hay is from the mid-western US.

Black Blotch Disease

The disease is more commonly found in clover pasture, however, alfalfa can get black blotch disease particularly in moist and hot conditions. It is caused by the Cymodothea trifolii fungus. ^[37]

This can lead to liver damage and secondary photosensitivity in horses, particularly those with light coloured coats. ^[35]

When to Avoid Alfalfa

While alfalfa offers many benefits, some horses do not need such a nutrient-dense forage and may not tolerate alfalfa well.

Feeding horses that do not require a high protein intake free-choice alfalfa can lead to excessive nitrogen excretion. ^[32]

Horses with kidney or liver issues should not be fed high-protein diets as these diets require increased urine production to eliminate excess amino acids. In addition, high calcium should be avoided in horses with urinary sludge or kidney and bladder stones.

Horses that require a calorie-restricted diet to maintain an optimal weight should be fed grass forage rather than alfalfa. Alternatives such as grass hay, cubes, or pellets will better meet the needs of easy-keepers.

In addition, horses with metabolic concerns (especially those that are overweight) may not tolerate large amounts of alfalfa. Recent research shows that very high protein meals cause a high insulinemic response in horses with metabolic syndrome. ^[33]

Alfalfa hay is typically higher in potassium than mature grass hays. It should be avoided by horses with hyperkalemic periodic paralysis (HYPP), who require diets low in potassium. ^[34] If it must be fed, soaking the hay for an hour in cold water will considerably lower the potassium.

Example Diets

Below are example diets for mature 500 kg (1100 lb) horses with alfalfa hay included at no more than 20% of the forage. These diets use typical alfalfa hay (20% crude protein, 40% NDF) and grass hay (10% crude protein, 67% NDF).

Note that every horse has unique needs and each feeding situation has practical limitations. For help with designing the right feeding plan for your horse, submit their information online to receive free guidance from our equine nutritionists.

Healthy 500 KG Horse in Light Work

Horses in light to moderate work likely do not need alfalfa hay to meet their energy requirements, but they can tolerate small amounts. Adding too much alfalfa hay can lead to weight gain.

Mad Barn’s Omneity vitamin and mineral supplement is added to the diet to ensure vitamin and mineral requirements are met.

Omneity – Premix

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• Complete B-vitamin fortification
• Optimal nutrition balance
• Our best-selling equine vitamin

Healthy 500 KG Horse in Heavy Work

For horses in heavy work, forage may not be sufficient to meet their energy needs. Adding alfalfa cubes boosts the energy supply while serving as a carrier for calorie-dense oils.

In this diet, Mad Barn’s w-3 Oil is added as a palatable fat supplement enriched with the omega-3 fatty acid DHA and natural vitamin E.

w-3 Oil

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• Promotes joint comfort
• Helps to fight inflammation
• Skin & coat condition
• Palatable source of Omega-3's

In diets with a significant amount of alfalfa, we recommend using our vitamin and mineral supplement AminoTrace+ in place of Omneity. AminoTrace+ is a pelleted formula that is lower in calcium and will better balance high alfalfa diets.

500 KG Mare in Early Lactation (2 Months)

Alfalfa hay is a great way to add protein, energy and calcium to a mare’s diet while she is producing a high volume of milk. Oats and roasted soybeans are also good sources of calories.

After three months of lactation, the mare’s milk production will begin to decrease. At this time, the alfalfa hay and other calorie sources can be decreased depending on the broodmare’s body condition.

Summary

Alfalfa is a staple in many horse diets and can be an excellent source of energy, protein, and minerals for horses that have higher nutritional requirements.

Mature horses in light exercise may not need the higher nutrient density of alfalfa, but this forage can be incorporated into most feeding plans in small to moderate amounts as long as the diet is balanced properly.

If you are interested in adding alfalfa to your horse’s diet but are unsure of how to balance it properly, you can submit your horse’s information for evaluation by one of our professional equine nutritionists.