Akademik Veri Yönetim Sistemi
Veterinary Immunology and Immunopathology, cilt.297, 2026 (SCI-Expanded, Scopus)
Seasonal heat stress pre- and postnatally is associated with altered health and growth in dairy calves. This study investigated the potential associations between birth season and the inflammatory response and oxidative stress status in Holstein calves during the first 90 days of life. Calves born in summer (n = 20) and winter (n = 21) were monitored longitudinally. Blood samples were collected from the calves immediately after birth (before colostrum intake; hour 0), at 12 and 24 h, and subsequently on days 4, 6, 8, 15, 21, 30, 60, and 90. Total protein (TP), Brix percentage, inflammatory parameters (IL-17A, IL-10, IL-6, IL-1β, TNF-α, IFN-γ, haptoglobin, LPS), and oxidative stress markers (NO, PON1, TAS, TOS, OSI) were measured in serum samples. Data was evaluated using Linear Mixed Models. TNF-α, NO, and OSI levels were significantly higher in the summer group, while haptoglobin, IL-6, IL-10, IL-17A, and IFN-γ levels were higher in the winter group. PON1 levels increased after day 15 in both groups but remained lower in the summer group, potentially reflecting a depletion of antioxidant capacity. LPS and IFN-γ levels showed a decreasing trend from day 30, and IL-1β and IL-10 levels from day 60 until day 90. Serum TP and Brix values were higher in the winter group. In conclusion, the elevated acute-phase and cytokine responses coupled with more severe clinical findings in winter calves reflect a dysregulated inflammatory process due to higher infection pressures in winter conditions. The gradual decline in LPS and inflammatory mediators over time may associated with the maturation of the intestinal epithelial barrier and the achievement of immune homeostasis.