Giving some form of alfalfa before riding a horse with an empty stomach will likely have a positive impact and could reduce your horse’s risk of developing gastric ulcers. | Photo: Kevin Thompson/The Horse

Q. I feed my ulcer-prone horse alfalfa before riding, because I’ve heard the calcium in alfalfa works like a big Tums antacid to keep my horse’s stomach from hurting during exercise. I was recently told that alfalfa pellets don’t work and that I should use alfalfa hay or chop instead, because the alfalfa needs to create a “hay mat” in the stomach to keep acid from splashing up into a horse’s esophagus (basically, causing horse heartburn). Is it true that I need to feed alfalfa hay or chop instead of pellets?

A. You are correct. Alfalfa is typically high in calcium, which researchers have shown reduces stomach acidity due to its buffering capacity. In a study at Texas A&M University, 12 horses were assigned to one of two groups: a 1:1 ratio by weight of Bermuda hay and a concentrate feed or of alfalfa hay and the same concentrate feed.

Treatment periods lasted 28 days before horses switched to the other diet with a 21-day washout period between treatments. At the start of the study each horse went through a gastroscopy to determine whether they had gastric ulcers and, if so, their severity. Horses were rescoped after the 28-day treatment periods to determine whether any existing ulcers had improved or worsened or new ulcers had