The objective of this study was to analyze the stress effect, via administration of ACTH (adrenocorticotropic hormone), on quantity and quality of milk produced and also the indication of stress by alteration of cortisol level. Twelve milking goats were divided in two groups: six animals were subjected to intravenous application of 0.06 UI of ACTH/kg of LW (challenged) and six received placebo solution (control). The challenge occurred during milking with protocol application at 30, 60, 120 and 180 days from the beginning of milking; each date the levels of cortisol were evaluated 30 minutes before, at the application of ACTH, 60, 120 and 300 minutes after ACTH. The milk production was measured daily during 270 days and every twenty days the milk was collected for somatic cell count (SCC) by the direct method. The cortisol levels measured at -30 and zero minutes before ACTH applications were low and similar between the goat groups. However, after 60 minutes it was verified the effect of ACTH application, and cortisol contents of 61.37±6.65 versus 5.47±1.21 ng/mL and of 51.17±10.21 versus 4.67±1.21 ng/mL at 120 minutes. At 300 minutes, the cortisol returned to basal level. There was no significant difference of milk production, protein contents and milk fat; groups ACTH and placebo produced 1.37±0.59 and 1.38±0.63 kg of milk, respectively. The somatic cell count was not influenced by ACTH stress and presented values located within the range indicated for healthy animals. Punctual stress originated from ACTH application was verified, but without alterations of quantitative and qualitative nature of milk produced, indicating that management activities that punctually stress animals do not bring production impairment.
apoptosis; cortisol; placebo; milk
