Dietary chromium propionate has been proposed as a supplement to help improve insulin sensitivity in horses suffering from insulin dysfunction, particularly in aging or obese individuals. A study examined the use of chromium in 48 healthy Quarter Horse geldings age 3-8 years [Spears, J.W.; Lloyd, K.E.; Sicilian, P.; et al. Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration. Journal of Animal Science 2020, Vol 97, no. 4; 10.1093/jas/skaa095].
The daily diet of the study horses consisted of 0.2 kg/100 kg body weight of concentrate and 1.75- 2.0 kg/100 kg bodyweight of grass hay. The study compared effects of feeding chromium at various doses—0, 2, 4 or 8 mg.
At the start of the study and at Day 28 after an overnight fast, blood samples were obtained at 0, 2, and 4 hours after concentrate was fed. Those samples were evaluated for glucose, insulin and non-esterified fatty acids. On Day 42, the horses were given a glucose tolerance test.
Horses fed 2 or 4 mg chromium per day:
- Had lower plasma glucose than the other doses (none or 8 mg) at day 0.
- Had lower plasma glucose at 2 and 4 hours post feeding.
- Serum insulin was less at 4 hours after feeding compared to horses given 8 mg chromium.
- Following glucose infusion for the glucose tolerance test, serum insulin was greater for horses fed 2, 4 and 8 mg chromium.
In summary, feeding 2 or 4 mg of chromium propionate per day did increase insulin sensitivity following oral carbohydrate consumption. While the healthy, young horses in this the study were not insulin resistant, this study might be a jumping off point for further studies on use of chromium in metabolically challenged older horses.