Horse owners recently identified insulin resistance as a diet-related disorder that they find difficult to explain and manage. Day-to-day management of insulin resistance depends on two key points:
- Horses at risk for insulin resistance benefit from diets low in both starch and water-soluble carbohydrates; and
- Hay analysis and potentially hay soaking, together with an exercise program, can help affected horses lead healthier lives.
What many of us might not know is that minerals also play an important role in the development and control of insulin resistance by virtue of their antioxidant capabilities.
“Ingestion of diets high in starches and sugars can promote the production of inflammatory molecules, such as interleukin-1ß. Further, obese horses with a chronic, low-level state of inflammation are at risk of developing insulin resistance, and therefore laminitis,” relayed Kathleen Crandell, PhD, nutritionist at Kentucky Equine Research.
Ensuring that specific minerals are balanced in your horse’s diet will help build antioxidant defenses and combat inflammation.
Consider the following:
- Copper and zinc are required for the antioxidant enzyme superoxide dismutase to function. Zinc is a commonly deficient mineral in equine forages.
- Selenium, also frequently deficient in equine forages, is required for selenoproteins, such as the glutathione peroxidase enzymes. Selenium-containing enzymes are important and widespread antioxidants.
- Selenium, together with iodine, is required for appropriate production of thyroid hormones. Normal thyroid function is required for horses to respond to insulin appropriately, and hypothyroid horses are sometimes depressed and lethargic.
- Correction of magnesium deficiencies can make it easier to control insulin resistance.
- Deficiency of magnesium can contribute to the development of insulin resistance or make the condition worse in affected horses.
“Feeding insulin-resistant horses and getting the minerals into them without added calories can be challenging. I usually recommend adding some type of vitamin and mineral supplement to their diet,” said Crandell. For these horses, KER recommends the use of I.R. Pellet (Gold Pellet in Australia), a low-starch, low-calorie concentrated source of vitamins and trace minerals.
As Crandell suggested, feeding horses a “blanket” (general) mineral supplementation is reasonable because if selenium is low, then usually zinc and copper are low as well. Insulin-resistant horses are usually on almost all-forage diets and often not getting the minimum specified feeding rate of a commercial feed. (When fed as recommended, commercial feeds supply the minerals that may be low or missing in a forage-based diet, but many of these horses receive less than the minimum advised.)
Regardless of what approach is adopted, Crandell advised owners of insulin-resistant horses to “identify specific mineral deficiencies and correct those as soon as possible, ensuring that the balance between the minerals is also appropriate, particularly in the case of selenium.”
KER nutrition advisors can assist owners with ration evaluations. Get a free MicroSteed ration analysis.