This study was undertaken to examine serum and plasma Zn and Cu levels during 21 days after insemination. Presence of any relationship in plasma and serum concentrations of these trace elements between pregnant and non-pregnant cows was also investigated. The study was conducted on a total of 20 Swiss Brown cows. Equal number of pregnant and non-pregnant cows were used for serum and plasma extraction. Blood samples (10 ml) were collected three times a week from the jugular vein during 21 days after insemination. Zn and Cu concentrations and progesterone (P4) levels were determined using atomic absorption unit and RIA, respectively.

Serum Zn levels ranged from 0.33 ± 0.13 to 0.75 ± 0.14 mg/L and plasma Zn levels from 0.72 ± 0.15 to 1.23 ± 0.17 mg/L. The plasma Zn levels were always higher than those seen in the serum. Cu levels were found to be between 0.64 ± 0.08 - 0.77 ± 0.02ng/L in serum and between 0.46 ± 0.02 - 0.64 ±0.02 ng/L in plasma. The serum Cu levels were always higher than those of the plasma. The only significant differences (p<0.05) in serum Zn levels were observed on the day 4 between pregnant and non-pregnant cows. The results showed that plasma Zn levels significantly differed between the pregnant and non-pregnant cows on the days 9 (p<0.05), 18 (p<0.05) and 21 (p<0.005). In the pregnant cows, there were fluctuations in the serum Zn concentrations, but increases in those of the plasma on the days 18 and 21. The difference between the total serum Zn values of the blood samples collected during 21 days from pregnant and non-pregnant cows was found to be non-significant, but difference between the total plasma Zn values of the samples collected for the same period from other pregnant and non-pregnant cows was significant (P<0.05). Day 1 plasma Cu levels of the pregnant cows were found to be significantly higher than those detected on the days 4 and 5 of the non-pregnant cows (p<0.05). Serum and plasma Cu concentrations were not significantly different between the pregnant and non-pregnant cows. There was no correlation between serum and plasma Cu and Zn levels. Negative correlations were found in the serum Zn and P4 levels of the non-pregnant cows and plasma Cu and P4 levels of the pregnant cows.

In conclusion, the findings that plasma Zn levels were higher in early period of the pregnant cows than non-pregnant ones indicates that Zn has an important role in early pregnancy in cows. However, Cu concentrations did not show any significant variations in the early period of pregnancy.