Determination of antioxidant indices in dairy cows during the periparturient period

The aim of the present study was to evaluate indicators of antioxidant status – glutathione peroxidase (GPx); superoxide dismutase (SOD); total antioxidant status (TAS); vitamins A, E and beta carotene in 10 dairy cows of the Holstein breed from 15-20 days ante partum (a.p.) to 25–30 days post partum (p.p.). Blood samples were collected 5 × during this period: 15–20 days a.p., 1–3 days a.p., 2–3 days p.p., 10–15 days p.p. and 25–30 days p.p. The mean GPx activity was significantly ( P = 0.013) lower in the 10–15 days p.p. compared to 15–20 days a.p. ( P < 0.05) and 1–3 days a.p. ( P < 0.01). The increase of SOD values was monitored throughout the whole experiment. The mean TAS concentration was significantly ( P < 0.01) decreased 2–3 days p.p. compared to 25–30 days p.p. A significantly lower mean concentration of vitamin A was also found 2–3 days p.p. compared to the concentration 15–20 days a.p. ( P < 0.05) and 25–30 days p.p. ( P < 0.001). A significant ( P < 0.001) decrease in vitamin E concentration was recorded in cows 2–3 days p.p. compared to cows 15–20 days a.p. and 25–30 days p.p. The mean concentration of beta carotene was also decreased immediately after calving. Significant changes in the concentration of antioxidant parameters during the periparturient period indicate the occurrence of oxidative stress in dairy cows which can contribute to increased incidence of metabolic diseases.