Effect of season during late gestation on metabolic alterations, inflammatory response, and oxidative stress status in dairy cows and offspring

This study investigated oxidative stress, metabolic and inflammatory alterations, health status, and milk production in dairy cows that experienced heat stress in the dry period, and the effects on their newborn calves. The study material comprised 53 healthy Holstein cows, of which some experienced heat stress during the dry period (summer group; n = 25) whereas others did not (winter group; n = 28). The cows' body condition score and lactation number ranges were 3.0–3.5 and 2–5, respectively. Blood sampling for the cows was performed 21 days before the expected calving date and at the actual calving time, and for the calves immediately after birth (before colostrum intake) and at 24 h after birth. Each cow was sampled for colostrum from the first milking after calving. The serum samples of both cows and calves were analyzed for inflammatory parameters (haptoglobin, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-17A, IL-10, IL-6, IL-1β, interferon gamma (IFN-γ)), oxidative stress indicators (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase, nitric oxide (NO), paraoxanase (PON), total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI)), and metabolic parameters (total protein (TP), creatinine, albumin, bilirubin, cholesterol, alkaline phosphatase (ALP)). The colostrum samples were analyzed for both immunoglobulin G (IgG) and lactoferrin concentrations, while the calves’ blood samples at 24 h after birth were analyzed for IgG concentration. Comparing the summer and winter group animals, respiratory rates (70.8 + 13.3 and 42.4 + 6.8, respectively) and rectal temperature (39.6 + 0.4 °C and 39.0 + 0.3 °C, respectively) were higher in the summer group animals. The gestation length was 7 days shorter in the summer group than winter group (270.21 ± 6.69 days and 277.44 ± 4.26 days, respectively), while colostral IgG concentration was lower (154.17 ± 56.96 mg/dl and 224.51 ± 91.10 mg/dl, respectively). Metritis/clinical endometritis incidence was higher in summer group. Cows in the summer group presented with lower serum cholesterol, ALP, IL-10, TNF-α, OSI, and catalase levels, and increased serum TP, MDA, NO, SOD, and GSH-Px levels. Calves born to the summer group cows displayed decreased serum ALP activity and increased serum MDA, NO, catalase, IL-6, IL-10, IL-17A, IL-1β, and haptoglobin levels. In conclusion, experience of heat stress during the summer dry period led to: 1) induction of oxidative stress and disruption of metabolic processes in the dairy cows; 2) induction of oxidative stress and inflammatory reactions in their newborn calves; 3) higher incidence of postpartum health problems and milk yield losses in the dairy cows.