Q: My horse has been diagnosed with equine gastric ulcer syndrome. Is it true that alfalfa is better than grass hay for horses with ulcers?

A:  The short answer to your question is yes, adding alfalfa to your horse’s diet might be beneficial. Researchers at Texas A&M assessed the incidences of gastric ulcers in horses fed a pelleted grain concentrate and either coastal Bermuda (CB) grass hay or alfalfa. The horses in the study were Quarter Horse yearlings housed in small dry lots and subjected to exercise using a mechanical walker. They found the horses fed CB grass hay experienced a significant increase in ulcer score severity during the study period compared to the alfalfa-fed yearlings.

The composition of the alfalfa seems to help reduce the incidence of ulcer development and severity. Alfalfa is higher in protein and calcium than most grass hays, both of which act as buffers in the stomach, raising the pH level. Additionally, alfalfa is higher in a structural carbohydrate called lignin that is also thought to be beneficial. Other research has shown horses fed alfalfa hay and grain had significantly higher stomach pH for five hours after feeding and fewer/less severe gastric ulcers than horses fed brome hay. Raising the pH of the gastric contents reduces irritation of the sensitive squamous gastric tissue or existing gastric ulcers.

Not all barns offer alfalfa, and it might not be appropriate for all horses because it is higher in calories than most grass hays. Feeding too much alfalfa might result in a diet with very high crude protein and calcium levels, which can also be inappropriate for some horses. Researchers recommended feeding 1 pound of alfalfa to horses weighing 1,100-1,300 pounds after a grain meal because feeding grain, especially grains with higher nonstructural carbohydrate contents, lowers gastric pH, making the stomach more acidic.

Feeding a small amount of alfalfa is most easily done using alfalfa pellets or chopped alfalfa, especially if your barn does not provide alfalfa hay, because they are easily purchased in bags. Pellets or chopped alfalfa can be fed with grain meals or before exercise.

It is possible that very stemmy alfalfa could irritate the stomach. Research comparing the effects of particle size on the gastric mucosa in foals before and after weaning showed lesions at the pylorus were significantly more severe in the group fed alfalfa chaff (chopped alfalfa) than those fed alfalfa pellets. It’s important to note that in this study, the foals were fed just over 40% of the forage in their diet as alfalfa chaff or 37.5% of the forage as pellets, with the control group being fed 100% of their forage as grass hay. A subsequent study in a very small number of mature horses looked at the impact of feeding all the forage as either grass hay or chopped alfalfa and found no significant difference in glandular ulcer scores between the groups.

This research provides useful information as to the possible effect of alfalfa forage particle size on gastric health, but it is worth noting that in nonresearch settings, alfalfa chaff is typically fed as a supplement to the long-stem forage in much smaller quantities than was researched. Additionally, not all chaff is equal, in that some is quite soft and some is quite harsh. Larger forage particle sizes, such as those in chaff or from long-stem hay, will create a better raft of fiber on top of the stomach contents than pellets. Such a raft is important for reducing the likelihood of stomach acid splashing the sensitive squamous tissue, especially during exercise. Longer stems also require more chewing, which secretes saliva—a good stomach buffer.

If your horse is a good candidate for substituting some of the grass hay in the ration with alfalfa and your barn offers alfalfa, this might be a useful tool. Keep the alfalfa to no more than about 25 to 30% of the total forage intake to control total calcium and protein in the diet. If alfalfa hay is not a viable option for you or your horse, consider adding a small amount of alfalfa pellets or chopped alfalfa hay. Based on the particle size research, avoid chopped alfalfa if your horse has been diagnosed with pyloric ulcers. If alfalfa is not an option for your horse, there are many good commercial buffering feed supplements available on the market that use marine-derived calcium, which has been shown to be a very effective gastric buffer.

It is important to keep in mind that forage type and form is only one part of managing gastric ulcer disease in horses. Evaluate your entire management program to see where you can reduce stress (reductions in training intensity, isolation, negative human interactions, etc.), improve overall feeding management (small frequent meals, use of slow feed hay-nets), and alter environmental factors, such as increasing pasture turn-out. By conducting an inventory of your horse’s entire lifestyle and management and making changes where you can, your horse will have the best chance of gastric ulcer recovery and prevention.