Determination of cortisol concentrations using different biomarkers in dairy goats during pregnancy

Pregnancy is considered one of the most physiologically stressful periods in mammals. In the present study, serum and hair cortisol concentrations were measured in nine female Akkeçi goats, including five primiparous (1.5 years old) and four multiparous (3.5 years old), to evaluate chronic stress during pregnancy. Hair samples were collected in October, November, and December following the introduction of bucks to the herd and within the first 12 h postpartum (corresponding to the 1st, 2nd, 3rd, and 7th sampling times). Hair samples were not collected in January, February, or March (the 4th, 5th, and 6th sampling times) due to insufficient hair growth. Blood samples were obtained monthly between October and March during pregnancy and within the first 12 h postpartum. Both blood and hair samples were processed for hormone analysis in the laboratory. Cortisol concentrations in all samples were determined by enzyme immunoassay. The statistical analysis revealed no significant differences in serum cortisol concentrations between the sampling times or parity groups, whereas significant differences were observed only in hair cortisol concentrations among period means in the hair matrix (p < 0.01). Therefore, it was concluded that hair cortisol concentrations during pregnancy in Akkeçi goats represent a more reliable biomarker of long-term stress compared with serum cortisol concentrations.