Influence of chromium picolinate on glucose usage and metabolic criteria in growing Holstein calves
Bunting, L.D. | Fernandez, J.M. | Thompson, D.L. Jr | Southern, L.L.
Holstein calves, 10 steers (98 +/- 16 kg; Exp. 1) and 14 heifers (122 +/- 7 kg; Exp. 2), were fed either corn-cottonseed hull basal diets (CON; 15.1 and 13.2% CP, respectively) or CON plus 370 micrograms/kg of Cr as Cr-tripicolinate (CrP). After either 58 (Exp. 1) or 56 (Exp. 2) days of ADG and DMI measurement, calves were individually fed 1.4% of their BW every 12 h through the end of each experiment. Nitrogen balance, i.v. glucose tolerance tests (IVGTT), i.v. insulin challenge tests (IVICT), baseline growth hormone (GH) measurements, and GH-releasing hormone challenges were then performed on calves in split groups on d 70 through 87 in Exp. 1. In Exp. 2, all challenges began on d 78 and N balance was not determined. Inclusion of Crp did not affect (P > .10) ADG, DMI, or ADG/DMI of pooled data from Exp. 1 and 2 or N balance criteria in Exp. 1. Plasma glucose, insulin, and NEFA concentrations were not affected (P > .10) by Crp. Total plasma cholesterol was lower (P < .05) for Crp- than for CON-fed calves at wk 4 in Exp. 1 and wk 6 in Exp. 2. During IVGTT, calves fed CrP vs CON had higher (P < .05) clearance rates for glucose in Exp. 1 (2.68 vs 1.88%/min) and in Exp. 2 (2.64 vs 2.08%/min). During IVICT, calves fed CrP vs CON had higher clearance rates for glucose in Exp. 1 (2.98 vs 2.34%/min; P = .12) and in Exp. 2 (2.89 vs 2.00%/min; P < .05). The insulin responses of calves to IVGTT or IVICT were not affected (P > .10) by treatment. Measurements of GH secretion were generally not affected (P > .10) by CrP. Chromium picolinate supplementation may reduce plasma cholesterol and enhance glucose clearance from the blood of growing calves.
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