• “The majority of mature horses, those in light work or at rest, do not need to be fed grain or calorically dense fortified feeds. However, for those competition horses in hard work or lactating broodmares grain may be necessary in order to maintain condition.

• Feed ingredients high in starch and soluble sugars such as corn and molasses need to be digested and absorbed in the horse’s small intestine. Due to the relatively small size of the horse’s stomach, it is easy for it to be overwhelmed by large grain meals resulting in feed rapidly reaching the small intestine.

• In turn, if the absorptive ability of the small intestine is overwhelmed then these highly fermentable feed components will reach the hindgut where they can disrupt microbial fermentation. This may cause hindgut acidosis, colic, laminitis, and possibly colitis.

Getting creative with your horse’s dinner!

• The 2007 National Research Council guidelines state that “to avoid the decrease in large intestinal pH, high starch feeds should not be offered in amounts that result in significant starch overflow to the large intestine.”

• They go on to quote research that suggests the capacity of the small intestine may be reached at starch intakes of 3.5-4 g/kg body weight. However other research suggests this may be too high and that the small intestine may be overwhelmed at levels as low as 2 to 3 g/kg body weight.

Mixing supplements and feed.

• As many feeds do not state the starch content on the bag it can be hard for the general consumer to know just how much starch their horse is consuming at any one meal. For this reason, a general rule of thumb is that for a 1000 lb horse, no more than 5 lbs of grain/fortified feed should be fed at any one meal. For many commercial feeds, this is only about 1.5 average scoops, so if you are feeding 2 scoops at one time you may be overdoing things.

If you add water to meals, measure the weight before the water.

• I have found that even at or below the 5 lb rule of thumb some horses appear to display the symptoms of hindgut acidosis.

• I think that sometimes this can be due to the feeding of grain hays which can be high in starch, and other times it may be due to the fact that an individual horse may have a faster rate of passage of feedstuffs through the digestive tract than other horses.

• If this is the case then that feed will reach the large intestine more quickly. They are all individuals and have individual variation in exactly how quickly feed passes through their digestive tract.

• If you have a horse who needs grain to maintain condition, having a qualified equine nutritionist evaluate your program can help to ensure that you are not putting your horse’s digestive tract at risk. They will work with you not only to find appropriate feeds but also to create an appropriate feed management program.”

You can find more great information from Dr. Thunes on her website, Summit Equine Nutrition.