Effects of chromium supplementation to beef cows during gestation on beef cow performance and progeny development before weaning1

Angus-cross cows (n = 66) were fed 1 of 2 supplements through mid and late gestation: (1) 1.81 kg/d of corn as fed (control) or (2) 1.81 kg of corn fortified with 3 mg/d of Cr as fed (Chrom). Chromium supplementation did not affect (P ≥ 0.24) pre- or postpartum cow BW or BCS, or BW and BCS change. There was an interaction (P < 0.01) of days in gestation and Cr supplementation for glucose concentrations only. During mid gestation, plasma glucose concentrations in cows fed Chrom decreased 0.282 mmol/L compared with cows fed control; however, by late gestation, glucose concentrations in cows fed Chrom increased 0.321 mmol/L compared with cows fed control. Supplementation with Cr did not affect (P ≥ 0.58) insulin concentrations or insulin:glucose; however, insulin and glucose concentrations were reduced (time effect; P < 0.01) as days in gestation increased, regardless of Cr supplementation. There was no effect of dam treatment on calf BW at birth (P = 0.40) or weaning (P = 0.56). Chromium supplementation did not affect (P ≥ 0.20) estimated 24-h milk weight in mid or late lactation. Milk composition was not affected (P ≥ 0.25) by Cr at mid lactation. In late lactation, cows fed Chrom had greater (P = 0.01) milk urea nitrogen compared with cows fed control, with no other differences observed (P ≥ 0.23). In this experiment, supplemental Cr during gestation did not affect cow BW, BCS, milk production, or calf birth and weaning BW. Regardless of treatment, as cows neared parturition, plasma glucose and insulin concentrations of cows decreased.