The Importance of Fiber in Horse Diets

The Importance of Fiber in Horse Diets

Grazing is a full-time job for horses. Given their druthers, they would graze for 12 hours or more every day, their broad, flat teeth and sideways chewing motions making short work of the tough, stemmy grasses and weeds they favor.

Photo: Adam Spradling/The Horse

Grazing is a full-time job for horses. Given their druthers, they would graze for 12 hours or more every day, their broad, flat teeth and sideways chewing motions making short work of the tough, stemmy grasses and weeds they favor. Like all true herbivores, horses get most of their daily energy requirements from eating plant fibers.

While we often provide grain and supplemental fats to our domestic horses to give them the energy to do hard work, it’s important to remember that horses were meant to use fiber as fuel—and fiber remains the most important ingredient in every equine diet.

It provides energy horses need for everyday maintenance metabolism: ordinary functions such as breathing, walking, grazing, and sleeping. Without adequate fiber the horse’s digestive system doesn’t function properly and he is at risk of developing ulcers.

Fiber should make up at very least 50% (by weight) of a horse’s daily diet. And for the vast majority of adult horses, that percentage can be pushed considerably higher—even to 100% if the horse is an easy keeper and/or is not being asked to do work.

The basic principle is this: Grain is an optional part of a horse’s diet; roughage (fiber) is not. Yet, ironically, horses can’t digest fiber. In fact, no animal can digest fiber on its own. Animals don’t produce the enzymes needed to break the beta bonds of polysaccharide fibers and make the nutrients within available for use. Fortunately, horses, like most other animals, have thousands of invisible allies—a population of intestinal bacteria that resides in the cecum and colon and is specially adapted to digest the fiber that horses cannot digest.

Through a fermentation process, these gut flora produce the necessary enzymes to convert fiber to volatile fatty acids (VFAs) the horse can absorb. Not only do the bacteria benefit (making this a truly symbiotic relationship), but the VFAs they create provide between 30% and 70% of the horse’s total digestible energy needs.

But not all fiber is created equal. In a future article, we'll review how to assess the quality of the fiber in your horse's diet.

About the Author

Karen Briggs

Karen Briggs is the author of six books, including the recently updated Understanding Equine Nutrition as well as Understanding The Pony, both published by Eclipse Press. She's written a few thousand articles on subjects ranging from guttural pouch infections to how to compost your manure. She is also a Canadian certified riding coach, an equine nutritionist, and works in media relations for the harness racing industry. She lives with her band of off-the-track Thoroughbreds on a farm near Guelph, Ontario, and dabbles in eventing.

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