RESUMO
Background: Currently, rectal palpation is the cheapest and most convenient method which is using for detecting most of internal diseases, gynecologic conditions and artificial inseminations in dairy cows. However, rectal palpation procedure is probably painful, resulting in physiological and behavioral stress reactions. The life and metabolic activity can be affected by the oxidative stress which is one of the stress-related negative outcomes and characterized by the accumulation of radical oxygen species. Many factors such as stress, diet, antibiotics and husbandry practices effect animals' health and growth performance. The aim of the study was emphasized to the effects of rectal palpation related to stress response and oxidant/antioxidant status in dairy cows. Materials, Methods & Results: The study was conducted on ten 3-4 years old, non-pregnant Holstein dairy cows. The rectal palpation procedure was performed in a closed area using the traditional method. Blood samples were taken from each animal, an hour before and just after the rectal palpation procedure for detecting white blood cell, red blood cell, hemoglobin levels, hematocrit value, total antioxidant status, total oxidant status and nitric oxide, glucose and total cholesterol levels, as well as the plasma cortisol concentrations. WBC, RBC, Hct and Hb values were measured from whole blood by using an automatic blood count device. Plasma TAS and TOS levels were determined using a commercially available kit. Nitric oxide decomposes rapidly in aerated solutions to form stable nitrite/nitrate products. Plasma nitrite/nitrate concentration was measured by a modified method of Griess assay. Plasma cortisol concentrations were determined using an ELISA kit. Glucose and total cholesterol levels were analyzed in serum by using an auto-analyzer. White blood cell levels and hematocrit values were significantly increased just after the rectal palpation procedure compared to the baseline values (P < 0.05) whereas no significant difference was found in red blood cell levels and hemoglobin concentrations. Serum cholesterol concentrations have decreased after rectal palpation, serum glucose and cortisol concentrations have significantly and markedly increased (P < 0.05), the relevant variation factors were 13.41% and 23.26% respectively. Moreover, a remarkable and significant increase in the circulating TOS compared to the baseline values (P < 0.05 variation factor 31.78%) was observed after rectal palpation. In parallel, the nitric oxide concentrations were also significantly increased after rectal palpation procedure (P < 0.05 variation factor: 13.51%) On the other hand, the total plasma antioxidant status was depressed and the variation intensity remained weak (variation factor: -7.24%). Discussion: In the present study the results indicate that the rectal palpation procedure will be considered as a stressful condition, as evidenced by the strong increases in circulating cortisol, TOS and NOx concentrations associated with decreases in TAS concentrations. In addition, increased plasma cortisol concentrations in response to rectal palpation could be an additional factor responsible for the oxidative stress amplification. A more comprehensive identification of the physiological changes during rectal palpation could be beneficial for further researches in terms of accurate management practices in cattle practices and industry. Moreover, the determination of the oxidative stress parameters could provide novel approaches for the evaluation the stress in cattle.