Effects of flunixin and florfenicol combined with vitamins E and/or C on selected immune mechanisms in cattle under conditions of adaptive stress

The aim of the study was to evaluate the effect of flunixin and florfenicol administered in combination with vitamin E or C on selected leukocyte immune mechanisms and on the inflammatory process during the first few weeks in the feedlot. Fifty calves divided into 5 groups (n = 10) received florfenicol and flunixin with vitamin E or C. Blood was collected on the 1^st, 3^rd, 7^th, 14^th, 21^st, and 28^th d of the experiment. Intracellular metabolism (NBT), apoptosis, chemotaxis, susceptibility to M. haemolytica leukotoxin, and expression of β₂-integrins were determined in leukocytes. The symptoms of respiratory tract infection were observed in 40% of calves in control group, while in the other groups the morbidity rate ranged from 10% to 20%. Leukocytes showed decreased NBT, and the mean values for apoptosis ranged from 14% to 24%. The lowest percentage of apoptotic cells was observed in the calves that received florfenicol with flunixin and vitamins E and C. The chemotactic activity confirmed the significant inhibitory effect of the preparations on migration of the cells. A significant decrease (P ≤ 0.05) in the susceptibility of leukocytes to leukotoxin was noted in the group that received florfenicol and flunixin with vitamin E. Expression of β₂-integrin receptors was the lowest in calves receiving florfenicol with flunixin and vitamin E or C. The application of an antibiotic and a non-steroidal anti-inflammatory drug with antioxidants protected the leukocytes involved in defence against M. haemolytica virulence factors and effectively limited oxidative stress in the calves.