Abstract
The main purpose of this study was to evaluate different concentrations of Pb in blood serum on antioxidant status and intensity of lipid peroxidation in lactating cows. The object of the study is the Holstein cows (n=45; age-3-4 years). The period of blood serum sampling is 20-40 days after calving. The concentration of Pb in blood serum was determined by atomic emission and mass spectrometry (AES-ICP and MS-ICP). The activity of superoxide dismutase and the concentration of malondialdehyde were studied by spectrophotometric method on Stat fax 1904 Plus. Based on the data on the concentration of Pb in the blood serum, in accordance with the recommendations of Skalnaya (2003), cows were divided into three groups: I-Pb concentration up to the 25th percentile, II-within the 25th-75th percentile, III-above the 75th percentile. At the same time, the actual range of Pb concentrations in blood serum of cows of group I ranged from 0.00028-0.00049 µg/mL, II from 0.00053 to 0.00089 µg/mL, group III from 0.00094 to 0.0018 µg/mL. It was found that as the concentration of Pb in blood serum increased from the lowest (I group) to medium (II group) and high (III group), there was an increase in the concentration of malondialdehyde in blood serum from 42.5±12.9μM/L to 47.8±15.22µM/L and 57.9±11.2% (P£0.05) µM/L, respectively, the level of activity of the antioxidant defense enzyme, superoxide dismutase, decreased from 1,971±203.8% to 1,890±290.3% and 1,829±283.8 (P£0.05)%. The calculation of Spearman's rank correlation coefficients confirmed the statistically significant (P£0.05) degree of influence of Pb on the malondialdehyde (r=0.63) and superoxide dismutase activity (r=-0.57) in blood serum of cows. Thus, it can be stated that an increase in the concentration of Pb in the blood serum reduces the level of antioxidant protection and contributes to the development of oxidative stress in lactating cows.