Comparison of oxidative stress markers between single and twin gestations in Dorper ewes during pregnancy, delivery and postpartum

•Activities of antioxidant enzymes differed according to foetal number and time.•The thiobarbituric acid reactive substances concentration was lower in ewes with twin pregnancy.•The enzymatic activity of superoxide dismutase was higher in single pregnancy ewes.•As pregnancy progress, so does the antioxidant potential.•In single and twin pregnancies greater superoxide dismutase activity were observed at delivery and 24 h postpartum. Pregnancy in sheep is a physiological condition characterized by a significant increase in energy demand to ensure adequate foetal growth and development, making them susceptible to oxidative stress. The aim of this study was to analyse the markers of oxidative stress in sheep during pregnancy, parturition and close to peripartum (up to 48 h postpartum), comparing single with twin gestation. Sixty healthy Dorper ewes from 2 to 5 years’ old raised under semi-intensive management were used in this study. Ewes were grouped based on foetal number: Group 1, with single pregnancy (n = 30); Group 2, with a twin pregnancy (n = 30). Blood samples were collected nine times: after artificial insemination (D0, control); at 30 days (D30), 90 days (D90), 120 days (D120), 130 days (D130), and 140 days (D140) of pregnancy; on the day of delivery (DD); at 24 h (PD1) and 48 h (PD2) post-delivery. The concentrations of reduced thiol groups (-SH, P = 0.0155), the enzymatic activities of superoxide dismutase (SOD, P = 0.0009), glutathione peroxidase (GSH-Px, P = 0.0110) and catalase (CAT, P = 0.0001) differed according to fetal number by time. Twin gestation decreased concentration of thiobarbituric acid reactive substances (TBARS; P = 0.0278), and TBARS had differed over time (P