Effect of organic zinc supplementation on hematological, mineral, and metabolic profile in dairy cows in early lactation.

The aim of the current trial was to evaluate the effect of organically chelated zinc - methionin (Zn-Met) supplementation (30 mg Zn /kg DM TMR) on hematological, biochemical, and mineral profile of dairy cows in early lactation (1 - 90 d p.p.). Twenty dairy cows were randomly allocated to one of two dietary treatments in a randomized design. Animals in group C were treated as control (no zinc supplementation); whereas animals in group S were supplemented with organic Zn. Zn-Met supplementation had a significant effect on hematological parameters. White blood cell (WBC) counts 60 days p.p. and red blood cell (RBC) count, hemoglobin concentration (HGB), hematocrit level (HCT) and platelet count (PLT) on calving day, 30th- and 60th- day p.p were significantly higher in cows fed Zn than in the control group. In calves from supplemented mothers, there was a significant increase in RBC (p≤0.001), HCT (p≤0.01) and MCV (p≤0.05). There was no difference in other parameters among the groups, except of the highly significant difference in Zn concentration in blood serum of the S-group during the entire experimental time. The results obtained confirm the beneficial effect on serum zinc level and hematological parameters with no negative effects of 30mg Zn/kg TMR addition on mineral and biochemical parameters.