Oxidative stress markers and acute phase proteins in dairy calves undergoing different vaccination protocols against Bovine Respiratory Disease

Background. Bovine Respiratory Disease (BRD) represents a major health and economic concern in dairy cattle production. Objectives. To evaluate the effect of different BRD vaccination protocols on oxidative stress markers and acute phase proteins response in dairy calves. Materials and Methods. Three groups of calves were enrolled: control (CTR, n = 9), intranasal vaccine (INT, n = 25), and combined intranasal plus parenteral vaccine (VAC, n = 15). Serum samples were collected at T0 (10±2 days of life, dof), T1 (17±2 dof), T2 (31±2 dof for CTR/INT; 38±2 dof for VAC), and T3 (45±2 dof for CTR/INT; 52±2 dof for VAC). INT and VAC calves received the intranasal vaccine at T0, while VAC calves also received parenteral vaccination at T1 and a booster at T2. Serum Biological Antioxidant Potential (BAP), derivatives of Reactive Oxygen Metabolites (dROMs), Paraoxonase-1 (PON-1), and Serum Amyloid A (SAA) were measured. Oxidative Status index (OSi) was calculated as dROMs/BAP*100. Lung Lesion Score (LLS) assessed health status at T0 (LLS<10.5 = Healthy; LLS≥10.5 = Diseased). A mixed model included the fixed effects of group, time, health status, and their interactions. Post-hoc comparisons among least square means were adjusted with Bonferroni correction. Results. PON-1 increased over time (p<0.001), likely reflecting hepatic maturation. SAA showed a group*time*health interaction (p=0.03), but levels remained clinically irrelevant. BAP decreased after the first intranasal dose in vaccinated animals (time and group*time effects) (p<0.001). dROMs and OSi showed no significant changes, but levels were lower in non-vaccinated animals. Conclusion. Intranasal vaccination may consume antioxidant potential. PON-1 increase likely reflects liver development.