Acute Stress Response of Sheep to Shearing Procedures: Dynamic Change of Cortisol Concentration and Protein Electrophoretic Pattern

The current study aimed to investigate the influence of acute stress by shearing procedures on hematological parameters, serum cortisol concentration and serum protein electrophoretic pattern in Comisana sheep. A total of 20 not pregnant and not lactating adult ewes, aged 3−4 years old and with a mean bodyweight of 55.50 ± 3.50 kg, were enrolled in the study. From each animal, blood samples were collected before shearing (TPRE) and 5 (TPOST5) and 60 (TPOST60) minutes after the end of the shearing procedure in order to assess the values of hematological parameters, serum cortisol, total proteins and protein fractions, including albumin, α-, β1-, β2- and γ-globulins. According to statistical analysis results, albumin values were lower at TPOST60 than TPOST5 (p < 0.01), whereas α- and β2-globulins and the A/G ratio were higher at TPOST60 with respect to TPRE (p < 0.01) and TPOST5 (p < 0.01). A higher serum concentration of cortisol was found at TPOST5 and TPOST60 than TPRE (p < 0.01), and at TPOST60 than TPOST5 (p < 0.01). The serum cortisol values were negatively correlated with the serum values of albumin, β1-globulins and A/G ratio at TPOST60, and positively correlated with α- and β2-globulins at TPOST5 and TPOST60. The decrease in the albumin concentration and the increase in the α- and β2-globulins observed in ewes after shearing with respect to the baseline values suggests an acute phase response in shorn ewes. Additionally, the correlation found between the serum cortisol concentration and the serum protein fractions confirmed the immunomodulatory effect of this hormone, emphasizing the linkage between the endocrine and immune systems during an acute stress condition.