Many horses have health problems related to improper feeding. Feeding too much or too little, feeding the wrong kinds of feed, and feeding on schedules not conducive to good horse health can result in everything from laminitis to colic and many other medical problems.
According to N Striegel, D.V.M., Colorado State University Extension, It is best to feed horses only small amounts of high sugar/starch feeds (grains and concentrates) in frequent feedings. This feeding strategy provides for optimal equine digestion and fewer medical problems.
Although this suggestion may run counter to the schedules of many current horse owners because it may be difficult to divide grain feedings into three to four feedings per day, this is what is best for the horse’s digestive system.
Insulin resistance is treated and prevented mainly by nutritional changes and exercise. The insulin resistant horse should not be on any grain or high concentrate feed and they may need to be taken off pasture grass completely and only fed hay that is low in sugars and starch.
In these cases, hay should be tested for levels of sugar and starch because these are the highly absorbable carbohydrates in the diet that quickly raise the blood sugar and the insulin levels.
A proper hay would be a prairie hay or a second or third cutting of alfalfa hay processed after the bloom stage.The sugar content of any type of hay or a particular cutting of hay cannot be determined without testing the hay. Current thought is that a safe sugar content for sensitive horses is 10 percent or less. (Genrick et al.)
Feeds can be classified according to their “glycemic index”, which is an indicator of how a particular feed will elevate the blood sugar level and the subsequent blood insulin level after consuming it.
The elevated blood sugar and resulting insulin is called the glycemic response. Horses with insulin resistance should be on a low, glycemic index feed because they have an abnormal glycemic response after eating feeds that are high in sugar and/or starch.
In a recent study (Rodiek and Stull 2007), glycemic index values were determined for 10 feeds. A high index value predicts a high blood sugar response to this feed. They are listed from highest to lower:
Sweet feed
Corn
Jockey oats
Oats
Barley
In contrast, the following were shown to have lower glycemic index values (A low index value predicts a low blood sugar response to this feed). They are ranked from mid-range to lowest:
Wheat bran
Beet pulp
Alfalfa
Rice bran
Soybean hulls
A veterinarian that is familiar with your horse, the level of expected activity or work, and your priorities for the horse can advise you on what is the best way to feed your particular horse for optimal health and performance.