Metabolic effects of chromium supplementation in dairy cows in the peripartal period

Abstract

The aim of the work was to assess the effects of supplemental chromium (Cr) on metabolism of dairy cows in the peripartal period. Rations fed to dairy cows in a herd of Holstein cattle with mean milk yield of 7 500 1 were supplemented with chromium-enriched yeast (Co-Factor III Chromium Yeast, Alltech, 0.1% Cr3+) at 10 mg of Cr per animal per day. The treatment was started 21 days before the expected delivery date and discontinued 30 days after the delivery. Blood and urine samples were collected from ten experimental and ten control cows at weekly intervals, the state of health was monitored by regular clinical examinations, and milk yield for the first 100 days of lactation was recorded. The restdts indicate favourable effects of the supplementation on energy metabolism. The Cr-supplemented cows showed significantly higher blood glucose concentrations at post-partum (p.p.) weeks 4 (4.25 ± 0.21 vs. 3.74 ± 0.36 mmol·l-1; p < 0.01) and 5 (4.06 ± 0.41 vs. 3.64 0.28 mmol·l-1; p < 0.05) and lower ketone bodies concentration at p.p. week 4 (0.88 ± 0.11 vs. 1.38 ± 0.66 mmol·l-1; p < 0.05). The Cr-supplemented cows showed also significantly lower bilirubin concentration at p.p. week 2 (3.93 ± 0.84 vs. 6.47 ± 3.25 μmol·l-1; p < 0.05) and lower catalytic activities of aspartate aminotransferase at p.p. weeks 3 (1.37 ± 0.14 vs. 1.66 ± 0.20 μkat·l-1; p < 0.01) and 5 (1.16 ± 0.08 vs. 1.47 ± 0.18 μkat·l-1; p < 0.01) and lactate dehydrogenase at p.p. week 5 (27.35 ± 3.76 vs. 33.61 ± 5.6 1 μkat·l-1; p < 0.05). No effects on the metabolism of nitrogen substances or minerals, insulin concentration in blood serum, and blood Cr concentration were observed. Chromium excretion in urine increased after parturition; higher concentrations were found in Cr-supplemented cows at p.p. weeks 3 (7.14 ± 1.72 vs. 5.00 ± 1.26 μg·l-1; p < 0.01) and 4 (8.40 ± 3.13 vs. 4.04 ± 1.32 μg·l-1; p < 0.01). Although chromium supplementation in the peripartal period significantly improved variables characterising the energy metabolism, no effects on milk yield for the first 100 days of lactation or on the incidence of clinical diseases were demonstrable.