SUPPLEMENTAL CHROMIUM - ITS BENEFITS TO THE BOVINE IMMUNE-SYSTEM

Chromium (Cr) is an essential micronutrient for humans. Its main actio n is thought to be regulation of blood sugar, because Cr deficiency is associated with diabetic-like symptoms and Cr supplementation is asso ciated with enhanced glucose tolerance and insulin sensitivity. Cr def iciency is prevalent in North America because the diets of most people do not contain adequate levels of organic Cr and stressors, such as h igh 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 s usceptible to Cr deficiency, particularly during periods of stress. Th ese 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 pres ented in this paper suggest that Cr does not dramatically alter blood concentrations of insulin, growth hormone, or insulin-like growth fact or I in supplemented cattle. On the other hand, Cr seemed to reduce bl ood cortisol concentrations during highly stressful situations. This m ay have promoted improved insulin or insulin-like growth factor I sens itivity in target tissues such as muscle, mammary gland, and the immun e system. The practical implications of these results are that occurre nce of infectious diseases could be reduced and production potential i ncreased if the diets of high-producing, intensively reared cattle wer e supplemented with organic Cr.