Influence of chromium tripicolinate on glucose metabolism and nutrient partitioning in growing lambs

Twenty-four Suffolk lambs (average BW 38 +/- 2.7 kg; 16 ewes and 8 wethers) were fed either a corn-cottonseed hull-based control diet (CON) or CON plus 250 ppb of Cr as chromium tripicolinate (CrPic). Lambs were penned in groups of three and ADG and DMI were measured through d 85 of the experiment. Jugular blood samples were obtained during wk 2, 7, and 11. An i.v. glucose tolerance test (IVGTT; 500 mg of glucose/kg BW) and an i.v. insulin challenge test (IVICT; .1 IU of ovine insulin/kg BW) were performed during wk 2 and 10 of the trial. This was followed by a N balance trial during wk 3 and 11. Wethers were slaughtered at the end of the experiment and carcass characteristics determined. No differences (P > .10) were observed between dietary treatments in DMI, ADG, or N balance; however, the CrPic-fed wethers had 18% less fat over the 10th rib (P = .082) and a lower yield grade (P = .014). Plasma NEFA was lower throughout the trial (P < .03) and cholesterol was 17% lower during wk 2 (P < .02) in lambs fed CrPic. There were no differences due to diet (P > .10) in plasma concentrations of urea N, glucose, albumin, total protein, insulin, glucagon, triiodothyronine, or thyroxine. Glucose clearance rate and half-life during the IVGTT and IVICT did not differ (P > .10) between CON and CrPic groups; however, during the IVGTT on wk 2, plasma insulin was elevated (P < .05) and glucose reduced (P = .067) in the lambs fed CrPic. Supplemental CrPic seems to influence metabolic measurements that may affect performance of growing lambs.