Correlations of whole blood heavy metals with serum immunological and oxidative markers during the early dry period and transition period of dairy cattle.

Immunological and oxidative alterations have been reported around calving in dairy cattle. In addition, the levels of heavy metals rise in the blood around parturition, which might affect body systems. Therefore, in this Research Communication we evaluate the changes in whole blood lead (Pb), arsenic (As), and cadmium (Cd) around calving, in comparison with the beginning of the dry period, and assess the correlations of these elements with immunological factors and oxidative markers. Samples were collected from 30 clinically healthy dairy cows in the early dry period (-6 w), one week before expected calving (-1 w), and one week postpartum (+1 w). The highest concentrations of Pb, As, and Cd were observed at -1 w and all the three elements decreased after parturition leading to significantly lower As and Cd, compared to -1 w (P < 0.05). The lowest levels of tumor necrosis factor-alpha, immunoglobulin G, interleukin 4, interleukin 10 and haptoglobin were found at -1 w simultaneous with the highest measures of the heavy metals, with tumor necrosis factor-alpha being significantly lower at this time (P < 0.05). At -6 w, As concentration was significantly (P < 0.05) correlated negatively (r = -0.366) and positively (r = 0.417) with total antioxidant capacity and malondialdehyde, respectively. Furthermore, at -1 w Pb and As had significant (P < 0.05) negative correlations with interferon gamma (r = -0.502) and interleukin 4 (r = -0.483), respectively. After parturition, Pb was observed to be negatively correlated with total antioxidant capacity (r = -0.538, P < 0.05). The observed results revealed that the alterations in immunological factors and antioxidant capacity around parturition were correlated with Pb and As levels.