by Jesse Bussard

Horses have evolved over the eons into selective grazers, eating mainly grass, and are designed to survive on large quantities of low quality forages. It wasn’t until domestication of the horse somewhere between 2000-4000 BC that this diet changed.

The reason for this change was man. Early civilization found it more convenient to feed grain to their mounts because of it was energy dense, created less waste, and was easier to transport on long trips to battle. Since this sequence of events a grain ration has become commonplace in many equine diets, consisting of low fiber and high starch. This methodology, though convenient for owners and trainers, denies the horse its true biological design.

Scientific research has shown that this predilection to a low fiber high starch diet has negative implications on both equine welfare and behavior. Researchers at the University of Bristol in 2009 determined that diet and stable management play a major role in horse behavior. By allowing the horses to mimic an almost continuous natural grazing behavior similar to that of wild horses, by feeding more hay vs. infrequent and large high starch diets, researchers discovered that the horses displayed generally quieter behavior and fewer stereotypic behaviors like cribbing or weaving. Stereotypic behaviors are virtually unheard of in wild horses. This suggests that by increasing turnout times and social contact with other horses, stereotypical behaviors may be able to be deterred.

A 2010 study by Cornell University’s College of Veterinary Medicine found that when horses were fed pellets, they worked harder to obtain a hay food reward than when they were fed hay. In the study, horses fed hay spent 61.5% of their time eating versus only 10% for horses eating pellets. Horses fed pellets spent 58% of their time standing while horses fed hay spent 37% of their time standing. Horses fed pellets also spent 11.5% of their time sifting through bedding in their stall looking for food compared to only 1.2% for horses fed hay. The researchers determined that the horses fed pellet diets showed a “hunger for hay” while horses fed hay did not. This along with the previous study indicates that a reduction in dietary fiber can have major impacts on equine behavior and physiology.

All this being said, a high fiber, low starch diet may not work for all equines. Racehorses, high performance event horses, or hard keepers may require more calories than a high fiber, low starch diet can provide and will most likely require concentrates. For horses that do perform well on this diet, the benefits are many including an increase in digestive health and a lowered risk of metabolic disorders and laminitis.

So what qualifies a horse for a high fiber, low starch diet? Many horses of different breeds and disciplines may benefit. Many times horses that are easily excitable, hard to handle, obese, insulin resistant, or diagnosed with muscle disorders or hindgut acidosis make good candidates. An important thing to remember when considering change in a horse’s diet is to always consult a veterinarian or experienced equine nutritionist. Always recommend to your customers that abrupt or drastic changes in diet could have negative implications.

In the end, a high fiber, low starch diet isn’t going to work for every horse but we must not forget their true biological nature as grazers. Allowing horses to exhibit their natural grazing behavior through providing hay and increasing turnout time and social contact with other equines will make for happier, healthier horses.

This column was originally featured in the October issue of Tack ‘n Togs.  The pdf file can be accessed here.