Immune and oxidative parameters were evaluated as indicators of the influence of stress on the occurrence of respiratory syndrome in feedlot calves. The study was carried out on 60 2 and a half-month-old Simmentaler calves transported at feedlot. Mean daily feed consumption, daily weight gain, and behavioural activity were evaluated. Blood was collected on days 1, 3, 7, 14, 21, and 28 of feedlot. Serum NO ions, lipid peroxidation, acute phase proteins, IgG, and IgM were determined. The calves showed a decrease in feed consumption during the first 7 d of the feedlot. Sporadic stereotypies were noted. NO concentration showed a significant (P < 0.05) increase on days 7 and 14. Concentration of thiobarbituric acid reactive substances (TBARS) increased (P < 0.05) on days 1 and 3. IgM concentration was found to be considerably lower on days 14 and 28. Serum haptoglobin level showed a significant increase in stressed calves on days 1, 3, 7, and 14 of the feedlot. Based on these results, it can be suggested that stressors associated with transport and adaptation to the feedlot induce a stress reaction in calves, resulting in behavioural disorders, reduced weight gain, suppression of the humoral immunity and increased morbidity during the first weeks. These parameters seem to be crucial in evaluating the animals' health and welfare.
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 1st, 3rd, 7th, 14th, 21st, and 28th 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.
The study was performed on nasal swabs, tracheal samples, and sera obtained from young beef heifers aged between 6 and 12 months, from farms in eastern and south-eastern Poland. The samples were evaluated using bovine herpesvirus 1 (BHV-1) ELISA kits (ELISA BHV1 antibody and ELISA BHV1 antigen) and PCR. Among all the animals examined, 37 (32.2%) were positive in the ELISA BHV1 antigen test. The presence of BHV-1 was confirmed by PCR in 42 (36.5%) animals. In the ELISA BHV1 antibody test, 39 (33.9%) seropositive animals were identified. The presence of BHV-1 positive samples was observed in all the examined breeds of young cattle. There were no significant differences (P ≤ 0.05) in BHV-1 positive samples. The results indicate that the incidence of BHV-1 infections in feedlot cattle herds studied was 32.2%-36.5%, which suggests that preventive measures should be implemented in order to limit transmission of the virus.