Feeding Order of Forage and Oats: Is There a Right Way?

You’ve probably tossed countless flakes of hay and fed innumerable scoops of feed to your horse, but have you ever wondered if it is better to feed them in a particular order? Are there health-related advantages of feeding forage prior to concentrates? Concentrates prior to forage?

Researchers at the Norwegian University of Life Sciences set out to determine if one way was better than the other. They measured gastric emptying in horses in combination with metabolic responses in serum and digestive effects in the colon when they flip-flopped the feeding order of oats and timothy haylage.^*

Gastric emptying is the process by which the contents of the stomach are pushed into the duodenum or the first portion of the small intestine. In horses, gastric emptying has been a topic of interest to researchers for many years. They have discovered that diet composition and meal size affect gastric emptying in horses. The machinations of the stomach continue to be a priority among researchers because of the preponderance of problems associated with the organ, primary of which is equine gastric ulcer syndrome (EGUS).

Four aged Norwegian Coldblooded Trotter geldings were used in this study. All horses had longstanding cecal cannulas, which allowed researchers to take cecal samples and measure cecal pH. The horses were fed unprocessed whole oats once per day and late-cut timothy haylage three times daily. Oats and haylage were fed separately: either haylage first and oats an hour later or oats first followed by haylage 15 minutes later. This timeline allowed horses to finish the first meal of oats or haylage before being given the next.

Researchers measured gastric emptying through a “13C-acetic acid breath test,” a noninvasive technique in which a horse consumes a test meal containing a labeled form of acetate with a carbon-13 isotope. The horse’s breath is then analyzed for the presence of labeled carbon dioxide, allowing researchers to indirectly assess how quickly the stomach is emptying its contents, as the appearance of labeled carbon dioxide in the breath indicates the meal has passed into the small intestine.

Cecal fluid samples were collected, and cecal pH measured with a pH electrode. The electrode was placed directly into the cecum through the cannula, which measured and recorded pH continuously on sampling days. Jugular blood samples were used to measure plasma insulin and glucose concentrations.

Results from the 13-C acetic acid breath test revealed that feeding order affected gastric emptying, as haylage-then-oats took nearly twice as long to pass through the stomach than oats-then-haylage.

While no changes were noted in plasma glucose or insulin regarding feeding order, changes occurred in cecal pH. Researchers found that feeding oats before haylage may lead to a swifter reduction in cecal pH and a lower general cecal pH than the opposite feeding order.

In summary, the researchers noted, “Based on the results from this study and other relevant literature, it is recommended to feed forage before concentrate.”

What does this mean to the average horse owner? “To give your horse the best shot at a healthy gastrointestinal tract, offer a small flake of hay 30-60 minutes before giving feed if he does not have access to free-choice forage,” said Catherine Whitehouse, M.S., a nutritionist at Kentucky Equine Research.

According to Whitehouse, understanding these subtleties in gastrointestinal function can help horse owners better manage their horses, especially as horses spend far less time grazing than ever before.

“Chronic gastrointestinal problems often throw an otherwise healthy horse off its game. We are not talking colic here, but more subtle, elusive setbacks, such as gastric ulcers or hindgut acidosis,” she said. “Some horses are stoic, never allowing these issues to affect their demeanor or performance. By and large, though, most horses will have setbacks once these problems take hold.”

Thoughtful feeding is the first recommendation. “Easy management changes, such as feeding forage before concentrates or providing appropriate free-choice forage, can be made at little cost to the horse owner,” Whitehouse recommended. For others, strategic supplementation may be necessary. High-quality, research-proven products are available to help manage gastric and hindgut health.

^*Jensen, R.B., I.H. Walslag, C. Marcussen, N.W. Thorringer, P. Junghans, and N.F. Nyquist. 2025. The effect of feeding order of forage and oats on metabolic and digestive responses related to gastric emptying in horses. Journal of Animal Science 103:skae368.