Can they eat it? / Alfalfa
Can horses eat alfalfa?
Fine for most, careful with easy keepers and kidney issues.
Rich in protein and calcium; good for hard keepers, growing horses and nursing mares, too rich for a pony on air. Introduce slowly to avoid loose manure. Blister beetles in alfalfa hay (Southwest, Midwest) are a separate, deadly hazard: buy from a reputable source.
Loose manure with a sudden switch; blister beetles cause colic, mouth ulcers, frequent urination.
Why
Alfalfa is a legume rich in protein, calcium and energy, which makes it a valuable forage for hard keepers, growing horses and nursing mares. The same richness is the catch: it carries more protein and calcium than many horses need, and a sudden switch can loosen the manure. Its feed value also varies with cutting stage, so it is best judged by how the horse looks and performs over time.
How much is too much
For a 1,000 lb horse, a few flakes a day mixed into grass hay is a common starting point, with the total amount guided by the horse's weight and workload rather than appetite alone. A pony or miniature on air needs far less, often just a small portion or none at all. Metabolic and easy-keeping horses should have alfalfa limited or mixed with grass hay. Introduce any change gradually over one to two weeks.
Horses
Full-size horses in work or at pasture often do well on alfalfa, especially as a supplement for hard keepers, performance horses and mares in foal or nursing. Watch manure consistency after any switch, and keep the total ration balanced with grass hay so calcium does not climb too high. Buy hay from a reputable source and inspect each bale for blister beetles before feeding.
Ponies and easy keepers
Ponies, miniatures, seniors and insulin-resistant or laminitis-prone horses should generally avoid or strictly limit alfalfa because it is calorie and protein dense. Even small amounts can add more weight than these horses need. Where a senior horse cannot chew grass hay well, a soaked alfalfa cube or pellet can be a gentler option, with your vet guiding the amount.
Safe alternatives
Good grass hay such as timothy or orchardgrass is the everyday staple for most horses. Soaked beet pulp is a safe, low-starch fibre for easy keepers and seniors, served damp to prevent choking. A plain ration balancer can supply protein and minerals in measured amounts without the bulk of alfalfa.
Questions people ask
Can I feed alfalfa hay with grass hay?
Yes, a mix is common and often the most practical way to add protein and calcium. Start with a small share of alfalfa and increase slowly, watching manure and weight.
Is alfalfa safe after frost?
Frost-damaged alfalfa can be fine, but any hay that is mouldy, dusty or unusually dark should not be fed. Check quality carefully and ask your vet if you are unsure.
Could blister beetles be in my alfalfa hay?
They can, especially in hay from the Southwest and Midwest. Blister beetles are toxic and can be fatal, so inspect every flake and buy only from a source you trust.
Careful for horses means: fine in a small amount, prepared as described, and not for every pet; the details say when to skip it.
General information from veterinary guidance, not a diagnosis. If you are worried, call your vet or a pet poison line: ASPCA Animal Poison Control (888) 426-4435. Charges may apply.
Written by Hoofdeck editors · updated Nov 13, 2026 · from ASPCA Animal Poison Control, Merck Veterinary Manual and university extension guidance.