Alfalfa and a Healthy Gastric Environment in Horses

By Kentucky Equine Research Staff

Experts suggest that feeding alfalfa (lucerne) reduces the incidence and severity of gastric ulcers in the upper region of the stomach, known also as equine squamous gastric disease. While the buffering capacity of alfalfa hay is well documented, new research shows that horses in heavy work need more than alfalfa to maintain a healthy gastric environment.

In certain circumstances, the pH of the stomach can dip as low as 1 or 2, on the pH scale of 0 to 14, which is more acidic than grapefruit or tomato juice. The lower or glandular region of the stomach produces mucus to protect the lining. The upper or squamous region, however, is far more sensitive to sloshing acid, making it prone to ulceration. All horses are at risk of developing gastric ulcers, but this condition is particularly prevalent in horses involved in training and competition.

Recognizing the widespread welfare and economic effects of equine gastric ulcer syndrome (EGUS), Kentucky Equine Research developed several products to support stomach health. “Some of these products contain ingredients that neutralize excessive gastric acid, protecting the stomach lining by reducing acidity and providing a physical barrier due to coating properties,” said Catherine Whitehouse, M.S., a nutritionist for Kentucky Equine Research.

Altering the diet may also minimize EGUS. Nutritionists suggest:

• Feeding diets high in fiber (at least 1.5% body weight in forage);
• Offering stabilized rice bran or vegetable oil rather than high-starch feedstuffs for supplemental energy;
• Feeding several meals per day when possible; and
• Using small-hole haynets and slow feeders to make forage last through the night until breakfast.

Nutritionists sometimes recommend feeding alfalfa hay to help ward off EGUS. High levels of certain nutrients, including protein and calcium, reportedly help neutralize acid in the stomach.

According to Whitehouse, “The amount of calcium in alfalfa hay is often greater than 1% with a calcium-to-phosphorus ratio ranging from 3:1-6:1, whereas calcium in grass hay hovers around half that with a much tighter calcium-to-phosphorus ratio.”

Pure alfalfa hay is usually reserved for horses with high nutritional needs, as it would oversupply energy, protein, and minerals for many horses. “We typically recommend including only a portion of alfalfa in the diet and combining it with a high-quality grass hay,” advised Whitehouse.

According to a recent study, alfalfa pellets do not appear to buffer the stomach in heavily exercised horses as effectively as alfalfa hay might. The study, which was performed in France, included 80 trotters from four training centers randomly divided into two groups. Horses in the control group were fed their usual diet of free-choice grass hay and pelleted concentrate, which provided 4.5 ± 1.5 g of starch per kilogram body weight per day. In the alfalfa group, the diet was the same except half of the pelleted concentrate was replaced with dehydrated alfalfa pellets, providing only 2.3 ± 0.7 g of starch per kilogram body weight per day.

All horses were examined via gastroscopy to directly visualize the lining of the stomach. Ulcer scores were assigned on days 0, 21, and 42 based on a scale of 0 to 4, with 4 denoting severe ulceration. No other changes in management or training were made throughout the study period.

At baseline (day 0), 49 of the 80 (61%) horses had either no lesions or mild ulcerations, equivalent to an EGUS score of 0, 1, or 2. The remaining 31 horses (39%) had severe EGUS with scores of 3 and 4. At days 21 and 42, no significant effect of the diet on either healing or prevention of EGUS was detected.

Researchers theorized that alfalfa pellets did not provide a protective layer on top of the gastric contents as alfalfa hay or chaff does, which is believed to prevent splashing of acidic gastric contents on the sensitive squamous lining of the stomach. Giving some alfalfa hay or chaff before exercise will help buffer the acid and prevent damaging acid splash in the squamous part of the stomach. Additional protection may be provided by adding a research-proven gastric buffer, such as Triacton, to a small meal 30 minutes before work.

^*Julliand, S., M. Buttet, T. Hermange, and V. Julliand. 2021. Effect of replacing part of concentrates with pelleted alfalfa on squamous gastric ulcers in exercised trotters. Journal of Equine Veterinary Science 10:103556.