Element Before calving Before calving Top of lactation n=72 n=72 n=72 Cu Mean 17.11 16.75 17.69 SD 4.80 2.27 2.13 Zn Mean 225.64 26.59 24.10 SD 8.14 7.28 7.60

Table 2: The concentration of Cu and Zn in blood serum (μmol/L) of dairy cows from eastern Slovakia.