[ Editor’s Note: Our April/May edition (Issue 60, pp 8-10) provided guidelines on feeding the laminitis-prone and insulin-resistant horse. Holistic Horse Veterinary Advisor Joyce Harman, DVM, MRCVS, points out the recommended grains in that article are processed feed. She suggests considering whole grains instead, and reminds us there is no single formula that will work for every horse.]
Whole foods with their high fiber content generally have a lower Glycemic Index (GI) than processed foods. Whole raw oats would be expected to have an even lower GI, but have not been tested. From a holistic perspective, whole foods also contain many of the micronutrients and fats needed for digestion, as well as the energy of a complete food. Scientifically, this is much harder to measure, but improved health is usually seen clinically in horses fed whole foods rather than heavily processed foods.
Rice bran has been shown to have very low rise in equine blood glucose levels after feeding it (1).
Some data presented for horses show a lack of understanding of the GI, such as one that sets a GI of 100 for oats (2) while human GI are based on feeding pure glucose and setting 100 with that. Other equine GI are based on the glucose as the base (3).
Feeds such as soybean hulls do have a low GI, but are heavily processed and may contain residues from the chemical extractions performed to remove the oils for human consumption.
Oils have been shown in equine and human studies to be beneficial in insulin resistance and to provide a safe source of energy.
1. Glycemic response to rice bran in Thoroughbred horses. R Geor, J Pagan, K Hoekstra and D Nash. Proc. 17th Equine Nutrition and Physiology Society 1999.
2. Feed type and intake affect glycemic response in Thoroughbred horses. JD Pagan, PA Harris, MAP Kennedy, N Davidson and KE Hoekstra. Proc. 17th Equine Nutrition and Physiology Society 1999.
3. Glycemic index of cracked corn, oat groats and rolled barley in horses. E Jose-Cunilleras, LE Taylor and KW Hinchcliff. 2004. 82:2623-2629. J Anim Sci. http://jas.fass.org/cgi/content/full/82/9/2623