An evaluation of the effects of α-tocopherol and ascorbic acid in bovine respiratory disease complex occurring in feedlot calves after transport R. Urban-Chmiel a, ⁎, P. Hola a , U. Lisiecka b , A. Wernicki a , A. Puchalski a , M. Dec a , M. Wysocka a a Institute of Biological Bases of Animal Diseases, SubDepartment of Veterinary Preventive, Poland b Department of Epizootiology and Clinic of Infectious Diseases, University of Life Sciences Lublin, Poland article info abstract Article history: Received 2 February 2011 Received in revised form 5 May 2011 Accepted 6 May 2011 Taking into account the beneficial effects of antioxidants in reducing morbidity and mortality in calves, the aim of this study was to evaluate the effects of vitamins E and C on the development of the inflammation process and on selected defence mechanisms against infections induced by M. haemolytica. The study was carried out on 30 Simmentaler calves weighing about 100 kg, which received s.c. vitamin E (750 UI) or vitamin C (2.5 g/calf). In leukocytes obtained from the calves, sensitivity to the cytotoxic effect of M. haemolytica Lkt was evaluated using the MTT assay, expression of β 2 -integrin receptors on leukocyte surfaces was assessed, and metabolic activity was measured by the nitrotetrazolium blue test (NBT). Concentration of haptoglobin (Hp) and serum amyloid A (SAA) was estimated in the sera obtained. Analysis of the intracellular metabolism of the leukocytes showed no statistically significant differences compared to the control. A difference (p ≤ 0.05) was observed in the sensitivity of the leukocytes to the cytotoxic effect of Lkt in comparison with the control group. No differences were found in the percentage of cells sensitive to Lkt between the group given vitamin E and the calves which received vitamin C. The percentage of expression of β 2 -integrin receptors reached its lowest values on leukocytes isolated from the calves given vitamin E. The correlation between expression of β 2 -integrins and sensitivity of leukocytes to Lkt showed the greatest correlation on day 14 in calves given vitamin E, and on day 21 in calves given vitamin C. Analysis of Hp concentration in the sera showed no differences between the two groups of calves tested, but revealed differences (p ≤ 0.05) in absorbance values compared to the control on particular days of experiment. SAA concentration in the sera of calves from the group that received vitamin E was similar to that of the control on days 14 and 21 of the experiment. On days 3 and 7 of the experiment a significant (p ≤ 0.05) decrease was observed in SAA in the sera obtained from calves from the group given vitamin E compared to the control and the group given vitamin C. © 2011 Elsevier B.V. All rights reserved. Keywords: Bovine respiratory disease complex Antioxidants Vitamins E and C Calves 1. Introduction Respiratory disease complex is one of the main causes of increased morbidity and mortality in feedlot calves in the first weeks following transport and arrival at the feedlot. When defence mechanisms are disrupted due to environmental effects and infectious agents, calves become more susceptible to the infectious disease. It has been established that decreased antioxidant potential accompanied by an increase in oxidative stress parameters has an important role in the development of the syndrome during the first 3 weeks after transport (Chirase et al., 2004, Knowles et al., 1999). Our own previous research (Urban-Chmiel et al., 2009a) also confirmed that transport Livestock Science 141 (2011) 53–58 ⁎ Corresponding author. Tel.: +48 81 445 60 36; fax: +48 81 445 60 32. E-mail address: renata.urban@up.lublin.pl (R. Urban-Chmiel). 1871-1413/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2011.05.003 Contents lists available at ScienceDirect Livestock Science journal homepage: www.elsevier.com/locate/livsci