Chromium propionate enhances insulin sensitivity in growing cattle
2012
Spears, J.W. | Whisnant, C.S. | Huntington, G.B. | Lloyd, K.E. | Fry, R.S. | Krafka, K. | Lamptey, A. | Hyda, J.
Thirty-six Angus and Angus×Simmental heifers, averaging 291kg, were used to determine the effects of dietary Cr, in the form of Cr propionate (Cr Prop), on glucose metabolism and serum insulin concentrations following glucose administration. Heifers were stratified by body weight (BW) within a breed and randomly assigned to treatments. Treatments consisted of 0, 3, 6, or 9mg of supplemental Cr/d from Cr Prop. Based on dry matter (DM) intakes, the daily doses of Cr were equivalent to 0.47, 0.94, and 1.42mg of supplemental Cr/kg of DM. Heifers were individually fed a corn silage-based diet at a level of 2% of BW. Each heifer was also fed 0.45kg of a ground corn supplement daily that served as a carrier for supplemental Cr. Glucose tolerance tests were performed on d 44 of the study. Glucose was infused via jugular catheters at a level of 0.45g/kg of BW⁰.⁷⁵ over a course of 1 to 2min. Blood samples were collected at −10, 0, 5, 10, 15, 30, 45, 60, 90, 120, 150, and 180min relative to glucose dosing for glucose and insulin determination. Area under the glucose response curve was lower (1,603 vs. 1,964mg/dL per minute) in heifers supplemented with Cr from 0 to 45min following glucose challenge. Serum insulin concentrations were lower in Cr-supplemented heifers than in controls following glucose infusion. The molar ratio of insulin to glucose was also lower in Cr-supplemented heifers relative to controls. Serum insulin and serum insulin to glucose ratios did not differ among heifers supplemented with 3, 6, or 9mg of Cr/d. Results indicate that Cr Prop supplementation increased tissue sensitivity to insulin in growing heifers. Based on insulin sensitivity, Cr requirements (as Cr Prop) of growing heifers can be met by supplementing with 3mg of Cr/d or 0.47mg of Cr/kg of DM.
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