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A new study challenges the belief that equine athletes in training require a diet high in concentrates (grains or pelleted feed) to meet their nutritional needs.

Concentrate-based feeding programs provide reliable energy to hard-working horses, but they also carry certain health risks---such as colic, tying up and laminitis---and are associated with “hot” behavior and stereotypies0 such as cribbing and weaving.

To investigate the feasibility of maintaining an equine athlete on a diet free of concentrates, researchers at the Swedish University of Agricultural Sciences followed 16 2-yearold Standardbred horses as they entered training in preparation for harness racing. The horses were fed a free-choice forage diet along with a mineral supplement. The diet combined haylage, a small amount of alfalfa pellets to increase protein levels when necessary, and pasture grazing when it was available.

The researchers divided the horses into two training groups---one followed a conventional training protocol and the other was put on a less intense schedule. The goal for both groups, however, was to start competing in races as 3-yearolds. Throughout the study, researchers analyzed the nutrient value of the diet and monitored the horses for feed intake, growth, body condition and muscle glycogen content.

“Muscle glycogen is the carbohydrate energy storage in muscle tissue,” explains Sara Ringmark, PhD. “Low muscle glycogen content may impair performance capacity and induce fatigue at an earlier stage.”

The data showed that the forage-based diet met the recommended energy, crude protein and vitamins and mineral levels for working horses. In addition, horses in both training-intensity groups maintained normal body condition, growth rates and muscle glycogen storage function. None of the horses developed nutrition-related health problems when managed under normal conditions. And although racing performance wasn’t part of this study, the researchers note that all of the horses qualified for racing by the end of the twoyear study period.

Ringmark says the notion that equine athletes require concentrates may be rooted in the fact that, at one point in history, that was true: “I think it’s such a common assumption because forage for horses used to be of poor nutrient value. Back in the day, when it was not possible to harvest and store forage with a high nutrient quality and horses were working hard

To feed a forage-only diet requires an adjustment in daily feeding routines as well as modifications for individuals. Lean horses, for example, may need free access to forage 24 hours a day.

on the farm or in the forest, concentrates were absolutely necessary to fulfill a horse’s energy requirement.”

In modern times, however, improved production and storage methods have resulted in forage that is high enough in nutritional value to meet the needs of a horse in fairly intensive training. That said, switching to such a diet requires diligence.

“To feed a forage-only diet to an equine athlete you might need to adjust your daily feeding routines a bit and, as with concentrates, individual adjustments might be necessary,” says Ringmark. “Lean horses may need free access to forage 24 hours day. We also found that it was important to have enough feeding spaces in the paddock for all horses to consume enough.”

Ringmark adds that to ensure forage is high enough quality for equine athletes, “You may need to have a good dialogue with your feed producer about an earlier harvest, which is necessary to produce the high-energy forages required.”

Reference: “Effects of training distance on feed intake, growth, body condition and muscle glycogen content in young Standardbred horses fed a forage-only diet,” Animal, October 2017