Alfalfa is one of the most effective dietary tools for managing gastric ulcers in horses. Its high calcium and protein content naturally buffers stomach acid, and its physical structure helps protect the sensitive upper lining of the stomach. Veterinary guidelines from the European College of Equine Internal Medicine confirm that feeding alfalfa hay results in higher stomach pH and less damage to the squamous mucosa compared to grass hays like bermuda or brome.
Why Alfalfa Buffers Stomach Acid
The benefit comes down to chemistry. Alfalfa contains roughly 15 grams of calcium per kilogram of dry matter, which is about three times more than grasses and far more than wheat bran. It also packs around 178 grams of crude protein per kilogram, nearly double most grass hays. Both of these nutrients resist pH changes when they encounter stomach acid.
Protein works as a buffer because its molecular structure contains side chains that absorb hydrogen ions, the particles that make acid acidic. As gut bacteria break down protein, they also release ammonia, which further neutralizes acid. Calcium contributes additional buffering activity, though the exact mechanism is less well understood and likely relates to how the mineral is stored within the plant’s cells. The net effect is that alfalfa acts like a natural antacid in your horse’s stomach.
What the Research Shows
A randomized, blinded crossover study fed ten adult Warmblood horses either alfalfa hay or meadow hay for 21-day periods. Horses in the alfalfa group started with a median ulcer score of 1 on the lesser curvature of the squamous region (the area most prone to acid damage) and dropped to a score of 0 by the end of the trial, a statistically significant improvement. In the glandular region of the stomach, alfalfa showed no harmful effects either. The researchers concluded that alfalfa has no detrimental impact on mucosal integrity and appears safe for the glandular area as well.
This aligns with broader findings. Horses fed alfalfa hay alongside grain consistently show higher gastric pH and less peptic injury to the squamous mucosa than horses fed coastal bermuda or brome grass hay without grain.
The Fiber Mat Effect
Beyond chemistry, alfalfa provides a physical benefit. When a horse eats long-stem alfalfa hay, the fibrous material forms a mat that floats on top of the liquid stomach contents. This mat acts as a barrier, preventing acidic fluid from splashing up onto the unprotected squamous lining during movement. This “acid splash” is a major driver of squamous ulcers in horses during exercise, since the stomach compresses with each stride at trot and canter.
Feeding a small amount of alfalfa hay or chaff before a workout puts this protective layer in place when it matters most. Alfalfa pellets, however, do not appear to offer the same protection. Researchers believe this is because pellets break down too quickly and don’t form that floating fiber mat the way long-stem hay or chopped chaff does. If you’re using alfalfa specifically to protect against exercise-related acid splash, stick with hay or chaff rather than pellets.
How Much to Feed
You don’t need to switch your horse’s entire diet to alfalfa to get the ulcer-prevention benefits. Researchers have recommended feeding about 1 pound of alfalfa to horses weighing 1,100 to 1,300 pounds after a grain meal. As a general guideline, keeping alfalfa at 25 to 30 percent of total forage intake gives you the buffering benefits while controlling the overall calcium and protein load in the diet.
Timing matters too. Offering a few handfuls of alfalfa hay or chaff 20 to 30 minutes before exercise gives the fiber mat time to form and the buffering compounds time to start working. Many owners also feed a small alfalfa meal after grain to offset the acid surge that follows concentrate feeding, since grain stimulates acid production without providing much buffering in return.
Risks of Feeding Too Much Alfalfa
Alfalfa’s high calcium content is a double-edged sword. At 1.27% calcium on a dry matter basis, it has a calcium-to-phosphorus ratio of about 5.4 to 1. That’s within the acceptable range of 1:1 to 6:1 for horses, but it sits near the upper limit. Compare that to timothy hay at 0.48% calcium or coastal bermuda at just 0.19%.
The bigger concern is enteroliths, mineral stones that form in the large intestine. Diets high in alfalfa are a known risk factor because of the elevated magnesium and protein content. UC Davis veterinary researchers recommend keeping alfalfa below 50% of the total diet to reduce enterolith risk. Horses that have previously had surgery to remove enteroliths should not eat any alfalfa at all. Certain breeds and regions (particularly California and the southwestern United States) see higher rates of enteroliths, so geography plays a role in how cautious you need to be.
Excess protein from heavy alfalfa feeding also increases water consumption and urination, and can contribute to ammonia buildup in stalls, which affects respiratory health. For horses that are easy keepers or insulin-resistant, the higher calorie and protein content of alfalfa compared to grass hay may not suit their metabolic needs.
Hay vs. Pellets vs. Chaff
The form of alfalfa you choose changes how well it works against ulcers. Long-stem hay provides both chemical buffering and the physical fiber mat. Chopped alfalfa chaff works similarly, since the pieces are still large enough to float on stomach contents and form a protective layer. Pellets deliver the calcium and protein for acid buffering but fail to create the fiber mat, making them a weaker choice for pre-exercise protection. Cubes fall somewhere in between, depending on how tightly compressed they are and how well the horse chews them.
For ulcer-prone horses, the most practical approach is to use long-stem alfalfa hay or chaff as a strategic supplement, fed before exercise and after grain meals, while relying on grass hay for the bulk of daily forage. This gives you the buffering and protective benefits without the metabolic and enterolith risks that come with an all-alfalfa diet.