Horse owners sometimes find it necessary to change their horse’s feeding program–fluctuations in temperature, season, and performance level are just some of the reasons. But with the known link between diet changes and health conditions such as colic or laminitis, how can owners safely transition their horse’s feed without negatively affecting his health? Don’t worry. We’re here to help.

According to the National Research Council’s Nutrient Requirements for Horses, any changes in the amount or form of feed—including grain or concentrates, hay, and pasture—should be made gradually due to the horse’s sensitive digestive system. Gradual feed changes lessen the risk of colic due to digestive upset.

Additionally, the digestive system needs time to adapt to diet changes in order to best utilize nutrients in feed. For example, when adding fat rapidly to a horse’s diet, researchers identified an increased amount and greasy texture of feces; however, when they added fat slowly, these effects diminished.

When planning a feed change for your horse, consider these research-based tips:

• Grains: If you’re simply increasing the amount of grain your horse consumes, researchers suggest increasing the ration at a rate of one-half-pound per day. This is especially important when feeding high-starch diets. Conversely, grain reductions should be done gradually over a one- to two-week period, subtracting about a quarter pound every other day. If you’re changing the type of grain your horse consumes, the transition should take five to seven days. Replace 25% of the current feed with the new about every other day until completely switched over.
• Hay: There is very little published data on changing hay types or amounts. Still, it is best to make these changes gradually, especially when switching hay types (from a grass to legume variety, for example), replacing 25% of the ration with the new forage every couple of days.
• Pasture: When turning horses out onto lush pasture, limit their grazing time for several days to avoid digestive upset. Increase the amount of turnout time by one to two hours per day until they’re turned out for the desired time (be it all the time or just until they’re brought in for the night). Nutritionists also suggest turning out horses with a full stomach (achieved by feeding hay prior to turnout) to try to reduce their grass intake.

If you’re working with a veterinarian to manage a growing horse or an animal with certain health conditions, they might recommend changing feed at a different rate, depending on the individual scenario. If you have questions about switching feeds for a particular horse, consult an equine nutritionist or veterinarian to implement a safe method.

Take-Home Message

Switch your horse’s feed type or amount gradually over a period of time to minimize his risk of digestive upset. Plan any nutrient-dense dietary changes, such as lush pasture or grains high in starch, carefully to avoid health problems such as colic or laminitis, and to allow for maximum nutrient digestion.