Relationship between oxidative stress status and glycoprotein-associated pregnancy concentrations during the early pregnancy period in dairy cows

This study was planned to assess the possible relationships with pregnancy-associated glycoproteins (PAG) concentrations by the determination of the biomarkers of oxidative stress in the plasma of dairy cattle during the early period of gestation. Materials and Methods: Blood samples were collected from coccygeal vessels in pregnant (n = 54) and nonpregnant (n = 45) cows. Measurement of biomarkers of oxidative stress (LPO, GSH and SOD) was carried out in females using spectrophotometric method.Plasma PAG concentrations increased and continuously over the both periods investigated. There were significant differences between pregnant and non-pregnant groups (P < 0.001). The concentration of SOD were significantly lower (P< 0.05) in pregnant females from day 25 to 35 (7.08 ±0.31 U.ml-1) and day 36 to 50 after AI (6.6 ± 0.29 U.ml-1) compared with non-pregnant cows (7.59 ± 0.35 U.ml-1). Concerning the concentrations of LPO and GSH, the values obtained were also significant lower (P < 0.05) in pregnant females in the period 25-35 days post AI (122.7 ±10.27 μM and 6.46 ±1.24 μmol/min.ml-1, respectively) and 36-50 days post AI (108.05±6.17 μM and 6.2±0.77 μmol/min.ml-1, respectively) than in the non-pregnant females (124.8 ± 12.16 μM and 6.96 ± 0.92 μmol/min.ml-1, respectively).It was observed that the markers of oxidative stress tended to be higher in non-pregnant females compared with pregnant females during the early period of gestation in dairy cattle. Our results suggest the existence of a relationship among the concentration of oxidative stress markers and PAG during early pregnancy.