Supplemental chromium: its benefits to the bovine immune system

Chromium (Cr) is an essential micronutrient for humans. Its main action is thought to be regulation of blood sugar, because Cr deficiency is associated with diabetic-like symptoms and Cr supplementation is associated with enhanced glucose tolerance and insulin sensitivity. Cr deficiency is prevalent in North America because the diets of most people do not contain adequate levels of organic Cr and stressors, such as high sugar diets, strenuous exercise, and emotional and physical trauma, lead to loss of body stores of Cr in urine. Numerous recent studies from the University of Guelph have indicated that cattle also may be susceptible to Cr deficiency, particularly during periods of stress. These studies, summarized here, showed that when market-transit-stressed feedlot calves or periparturient and early lactation dairy cows were supplemented with organic Cr, improved production, immune status, and health were realized. Although more research is required to determine whether production-enhancing and immunomodulatory properties of Cr are related to improved glucose metabolism as such, preliminary data presented in this paper suggest that Cr does not dramatically alter blood concentrations of insulin, growth hormone, or insulin-like growth factor I in supplemented cattle. On the other hand, Cr seemed to reduce blood cortisol concentrations during highly stressful situations. This may have promoted improved insulin or insulin-like growth factor I sensitivity in target tissues such as muscle, mammary gland, and the immune system. The practical implications of these results are that occurrence of infectious diseases could be reduced and production potential increased if the diets of high-producing, intensively reared cattle were supplemented with organic Cr.