Oxidative antioxidant status during transition from late pregnancy to early lactation in native and cross bred cows in the Egyptian oasis [electronic resource].

Includes reference.

Markers of oxidative stress and antioxidant capacity could provide complementary information about the homeostasis of the animal than the other conventional metabolic parameters. The aim of this work was to assess the interaction between the oxidative stress and the encountered antioxidant status during transition from late pregnancy to early lactation in native and cross bred cows in relation to the local environment of the Egyptian oasis. The study was carried out on 22 pluriparous pregnant cows, of which 12 native (Balady) and 10 crossbred (Friesian x Balady). Blood samples were collected from the selected cows at the 4_5th month of pregnancy, then weekly throughout the last three weeks prepartum, at calving time and weekly through out the first three weeks post-calving. At the peripartum period, the overall mean of the sum of the concentrations of plasma a-tocopherol, β-carotene, ascorbic acid and the activity of erythrocytic superoxide dismutase (eSOD) were lower than those registered at mid-pregnancy in both breeds. Thiobarbituric acid reactive substances (TBARS) values as a marker of lipid peroxidation were higher at periparrum period than mid-pregnancy only in crossbred cattle, but it did not change in native cattle. Within the eripartum period, variations (F test) of concentrations of plasma a-tocopherol, β-carotene and the activity of eSOD were significant, which tend to minimize with a conversed corresponding peak of TBARS at calving in both breeds. Levels of ascorbic acid did not change throughout the peripartum period in native and crossbred cows. The correlation and linear regression analysis revealed that TBARS negatively interacted with a-tocopherol and did not interact with ascorbic acid in both breeds. The relation between TBARS concentration and each of β-carotene concentration and eSOD activity was significantly negative in native cows, but it was non-significant in crossbred cows. In conclusion, the peripartum phase in cows can impose oxidative stress as indicated by the increase of TBARS concentration accompanied by marked depletion in the antioxidants. Stress due to calving has a greater effect on this imbalance. Native cows are well prepared than crossbred cows to deal with the oxidative stress at the peripartum period.

Summary in Arabic.