By Kentucky Equine Research Staff
The digestive system of horses and ponies is designed to process forage for the majority of each day. With modern management practices, however, horses are often maintained in stalls and fed meals twice daily, which can be consumed in a few hours or less. Horses left without forage for more than four or five hours may develop gastrointestinal or behavioral problems.
One option for decreasing the amount of time a horse spends without forage is the use of slow feeders. A recent study showed that consumption time was up to 61% higher when ponies were given access to partially filled haynets than when fed hay on the ground.
Another study exploring the benefits of slow feeders tracked chewing patterns with various slow-feeding devices.* Those researchers hypothesized that haynets with smaller holes would increase chewing frequency compared with feeding on the ground. Chewing stimulates the production of saliva, which contains bicarbonate, a compound that buffers the acidity in the stomach. More chewing produces more bicarbonate.
“Horses continuously produce gastric acid but only produce saliva while they are chewing. Therefore, continuous chewing can help reduce the risk of gastric ulcers by producing bicarbonate in the saliva,” explained Ashley Fowler, Ph.D., a nutritionist for Kentucky Equine Research.
To test the hypothesis that haynets increase chewing and alter chewing dynamics, the researchers fitted eight horses with “chewing halters.” These devices recorded individual chews using a pressure sensor on the noseband. Horses were maintained in stalls and fed bermudagrass at 1.5% body weight twice daily at 8 a.m. and 4 p.m. The researchers calculated the number of chews per kilogram of hay, chewing duration (total time spent chewing per day), and the percent of chews completed in the first 120 and 240 minutes of feeding. Horses were fed using haynets with large holes, haynets with small holes, haynets with only a bottom hole, and unrestricted off the stall floor.
Contrary to the researchers’ hypothesis, the haynets did not increase chewing frequency. Horses fed from the small hole haynet, however, had a longer chewing duration than horses fed off the stall floor. Further, fewer chews were completed in the first 240 minutes of being fed for horses feeding from small hole haynets compared to haynets with a single bottom hole.
“This research shows that slow feeders do not increase the number of chews for a specific amount of hay, but the small hole haynet did lengthen the amount of time that the horse spent chewing. This study also found that the horses had an increased rate of consumption from the haynets with a single bottom hole, which means not all slow feeders are created equal and need to be carefully evaluated,” advised Fowler.
In addition to access to forage, another way of protecting the sensitive squamous region of the stomach from acid damage is by offering a product containing antacids and stomach-coating agents.
Fowler added, “The squamous, or upper, portion of the stomach has fewer protective mechanisms against acid compared to the glandular, or lower, portion of the stomach and is more susceptible to developing ulcers from acid splash. Along with stimulating alkaline saliva production, consuming forage also helps create a fiber mat in the stomach, providing a physical ‘splash-guard’ to stop the acid from spraying on the squamous mucosa.”
Reprinted courtesy of Kentucky Equine Research. Kentucky Equine Research is an international equine nutrition, research, and consultation company serving horse owners and the feed industry. Our goals are to advance the industry's knowledge of equine nutrition and exercise physiology, apply that knowledge to produce healthier, more athletic horses, and support the nutritional care of all horses throughout their lives. Learn more at https://ker.com.
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*Hart, R., A. Bailey, J. Farmer, and K. Dubenstein. 2024. Chewing analysis of horses consuming bermudagrass hay in different styles of slow feeders as compared to loose hay. Journal of Equine Veterinary Science:105133.
