Antioxidative and oxidative profiles in plasma and saliva of cows in different ages and hormonal status.

The aim of this study was to evaluate changes in the antioxidant status and oxidative stress parameters in plasma and saliva in order to investigate the physiological conditions of dairy cows. Blood and saliva were collected from clinically healthy female calves (n = 18), sexually mature, non-pregnant cows (n = 19), and pregnant dairy cows (n = 15). Spectrophotometric and spectroflurimetric analyses were carried out in the body fluids of these animals. The level of total antioxidant capacity (TAC) in plasma reached the lowest (p < 0.05) value in the group of sexually mature, non-pregnant cows (2.375 ± 0.500 μmol/g). A significant negative correlation (tau b = - 0.248, p < 0.05) was found between TAC values detected in plasma and saliva of examined animals. The highest (p < 0.05) mean values of thiol groups were detected in both plasma (0.007 ± 0.0015 mmol/g) and saliva (0.276 ± 0,116 mmol/g) of mature, non‑pregnant cows. Conversely, the highest (p < 0.05) levels of formylokinurenine concentration were detected in saliva (11.535 ± 3.785 μg/mg) and plasma (0.133 ± 0.0237 μg/mg) of pregnant dairy cows. A significant positive correlation (tau b = 0.255, p < 0.05) was also found between the bityrosine content detected in plasma and saliva of the examined cows. In conclusion, although with regards to antioxidant/oxidative parameters saliva reflects the content of plasma only in part, however it shows age-related differences that can be used in the description of the physiological status of cows.