Evaluation of diet as a cause of gastric ulcers in horses.

OBJECTIVE To measure pH, volatile fatty acid (VFA) concentrations, and lactate concentrations in stomach contents and determine number and severity of gastric lesions in horses fed bromegrass hay and alfalfa hay-grain diets. ANIMALS Six 7-year-old horses. PROCEDURE A gastric cannula was inserted in each horse. Horses were fed each diet, using a randomized crossover design. Stomach contents were collected immediately after feeding and 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, and 24 hours after feeding on day 14. The pH and VFA and lactate concentrations were measured in gastric juice Number and severity of gastric lesions were scored during endoscopic examinations. RESULTS The alfalfa hay-grain diet caused significantly higher pH in gastric juice during the first 5 hours after feeding, compared with that for bromegrass hay. Concentrations of acetic, propionic, and isovaleric acid were significantly higher in gastric juice, and number and severity of nonglandular squamous gastric lesions were significantly lower in horses fed alfalfa hay-grain. Valeric acid, butyric acid, and propionic acid concentrations and pH were useful in predicting severity of nonglandular squamous gastric lesions in horses fed alfalfa hay-grain, whereas valeric acid concentrations and butyric acid were useful in predicting severity of those lesions in horses fed bromegrass hay. CONCLUSIONS AND CLINICAL RELEVANCE An alfalfa hay-grain diet induced significantly higher pH and VFA concentrations in gastric juice than did bromegrass hay. However, number and severity of nonglandular squamous gastric lesions were significantly lower in horses fed alfalfa hay-grain. An alfalfa hay-grain diet may buffer stomach acid in horses.