A.A Chalmeh - Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
S Nazifi - Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
M Pourjafar - Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
M.R Zarei - Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

BACKGROUND: Glucocorticoids have several benefits in largeanimal medicine but apart from their benefits, there are severaldisadvantages attributed to the use of these drugs. Amongthe disadvantages, disturbance in protein metabolism is oneof the side effects of glucocorticoids which has been investigatedin human and laboratory animals. OBJECTIVES: Thereare no information regarding the effects of glucocorticoids onprotein metabolism in large animals. Hence, the present experimentalstudy was performed to evaluate the protein metabolismfollowing glucocorticoids administration in Holsteincalves. METHODS: Ten clinically healthy Holstein calves (6 to 8months old) were assigned into 2 equal groups (n=5), containingDexa and Iso. Dexamethasone (1 mg/kg, intramuscularly)and isoflupredone(1 mg/kg, intramuscularly) were administeredin Dexa and Iso groups, respectively, on two consecutivedays. Blood samples were taken at days 0 (1st drug administration),1 (2nd drug dministration), 2, 3, 5 and 7, from all studiedanimals. Sera were assayed for total protein, albumin, globulin,serum amyloid A and haptoglobin. RESULTS: Serum amyloidA and haptoglobinexperience significant increase after administrationof both drugs. Isoflupredone induced the synthesis ofserum amyloid A and haptoglobin more than dexamethasone(p<0.05). Serum concentrations of total protein, albumin andglobulin experienced significant decrease after infusion ofdexamethasone and isoflupredone (p<0.05). Circulating levelsof these proteins in Iso group were lower than Dexa one, significantly.CONCLUSIONS: Isoflupredone and dexamethasonecan induce the protein catabolism. Furthermore, the concentrationsof serum amyloid A and haptoglobin, as oxidative stressbiomarkers, increased following both drugs administrationsdue to their oxidation effects on proteins. Finally, the effects ofisoflupredone on the metabolism of proteins are significantlyhigher than dexamethasone in Holstein calves.

oxidative stress, protein catabolism, glucocorticoids, Holstein calves