Hair cortisol, dheydroepiandrosterone and progesterone concentrations in crossbred beef cows from calving to 100 days postpartum

Dehydroepiandrosterone (DHEA) and cortisol (C) are hormones secreted by the adrenal cortex after stress stimulation, and they are related to resilience and allostatic load. Hair steroids measurement has recently received increasing attention for measurement of chronic stress in dairy cows, as it offers the advantages of being noninvasive, fast, and able to indicate steroids levels over long periods [1]. Around the time of calving, cows experience a suite of stressful events, including regrouping, diet changes, parturition, and the onset of lactation; during the transition period, it has been demonstrated that primiparous cows behave differently and are more likely to experience negative health outcomes compared to multiparous cows [2]. The objects of this study were to evaluate C, DHEA and progesterone (P4) hair concentrations in crossbred beef cows from calving to 100 days post partum (pp), and to assess possible differences related with parity (primiparous vs multiparous cows). Six primiparous and five multiparous pregnant beef cows from a tethered stall were enrolled. Hair samples of the 11 cows were collected during the autumn/winter season by shaving at calving (T0) and every 20 days for five times (T1-T5), only on the re-growth area. Hair C, DHEA and P4 were analyzed by RIA [1]. No differences were detected in the hair re-growth among animals. Statistical analysis showed higher C concentrations in primiparous cows at calving (T0) and at 20 days pp (T1) compared to all the subsequent samples (p<0.05). C levels at T0 and T1 in primiparous cows (6.7\ub13.37 pg/mL and 7.9\ub13.16 pg/mL, respectively) were higher than in multiparous cows (4.2\ub13.76 pg/mL and 4.1\ub12.36 pg/mL, respectively) (p