Effect of chromium supplementation on production and metabolic parameters in periparturient dairy cows

The effect of supplemental chromium as chromium-methionine (Cr-Met) on prod uction and metabolic parameters was investigated in 48 cows from 28 d befor e expected calving date through 28 d of lactation. Average body weight (BW) was 730 +/- 61 kg before treatment. Treatments were supplementation of 0, 0.03, 0.06, and 0.12 mg of Cr as Cr-Met/kg of BW0.75. Dry matter intake inc reased linearly and quadratically during the prepartum and postpartum perio ds, respectively, and body condition score loss decreased linearly during t he postpartum period with increasing Cr-Met. Increasing Cr-Met supplementat ion caused quadratic increases in milk, fat, and lactose yields. Treatments did not affect concentrations of blood metabolites and liver triglyceride. Serum insulin concentration and molar ratio of insulin to glucose for cows receiving Cr-Met were lower than for cows not receiving Cr-Met, but they i ncreased quadratically with increasing Cr-Met. Glucose tolerance tests (GTT ) were conducted on d 10 prepartum and d 28 postpartum. Chromium-methionine supplementation attenuated insulin sensitivity prepartum and enhanced gluc ose tolerance postpartum, but not prepartum. Basal insulin concentrations f or cows receiving Cr-Met were higher than for cows not receiving Cr-Met dur ing the prepartum GTT. During the postpartum GTT, peak glucose concentratio n and clearance rate decreased and half-life (t1/2) and time to reach basal concentration (T) were prolonged quadratically by increasing Cr-Met. Addit ionally, peak insulin concentration, area under the curve, and molar ratio of insulin to glucose were higher for cows not receiving Cr-Met than for co ws receiving Cr-Met and t1/2 and T were shortened quadratically by increasi ng Cr-Met.