Redox balance and metabolic responses in pregnant ewes at different periods of the dry season in the tropics

Sa？etak The study investigated the influence of ambient temperature and gestation on the redox homeostasis and metabolic profile of Yankasa ewes during the dry season in a tropical savannah. Ten ewes were synchronised and bred at early-dry season and lambed during the late-dry season, so that each sampling period corresponded to different periods of the dry season. Thermal environmental parameters were recorded during the morning and afternoon hours. Blood samples were collected from the ewes at pre-, early (cold-dry) -, mid- (early hot-dry) and late-gestation (late hot-dry), week 3 (late hot-dry) and week 2 prepartum (late hot-dry); and postpartum (late hot-dry). Serum samples were analysed for malondialdehyde (MDA), superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx), thyroid hormones, cholesterol, triglycerides, non-esterified fatty acids (NEFA), alanine aminotransferase (AST), aspartate aminotransferase (ALT), creatinine and urea. The highest average ambient temperature was obtained at mid-gestation. Mid-gestation was characterised by significantly (P<0.05) higher MDA and NEFA levels, but lower SOD, GPx and T3 level. The AST and ALT activities were lower (P<0.05) at pre- and early-gestation than at prepartum and postpartum. Urea concentration was higher (P<0.05) at postpartum than early-gestation. Discriminant analysis revealed a higher level of misclassification of parameters between pre-gestation, late-gestation, prepartum and postpartum, but no classification error occurred during early- and mid-gestation. In conclusion, the ewes were more stressed at mid-gestation than any other stage of the gestation. Therefore, measures to mitigate the adverse impact of high ambient temperature on the dam should be adopted to prevent the occurrence of pregnancy-related disorders during the season