Relationship of concentrations of cortisoi in hair with health, biomarkers in blood, and reproductive status in dairy cows

摘要

Hair cortisoi has been used to measure chronic stress in dairy cows as it offers the advantage of being nonin-vasive, fast, and able to indicate levels of cortisoi over long periods. The aim of this study was to determine the associations between hair cortisoi with clinical disorders, reproductive status, and the development of subclinical endometritis in dairy cows. Furthermore, we aimed to determine the association between hair cortisoi concentrations and blood markers associated with metabolic status and acute inflammation. In experiment 1, cows (n = 64) were hair sampled every 3 wk from the tail switch beginning at calving (d 0) until d 126 for cortisoi analysis; blood samples were collected every 3 wk from d 0 until 42 for f3-hydroxybutyrate and glucose analysis. In experiment 2, cows (n = 54) were chosen retrospectively by diagnosis of subclinical endometritis (END), subclinical endometritis and at least 1 clinical disease (END+CLIN), or as healthy (control) using a cytobrush and ultrasonography at 30 ± 3 d in milk. At the same time, animals were hair sampled for cortisoi analysis and blood sampled for haptoglobin and ceruloplasmin analysis. Health records were recorded throughout both experimental periods. Animals with clinical disease presented higher cortisoi concentrations than clinically healthy animals in experiment 1 [geometric mean (95% confidence interval); 8.8 (7.8, 9.9) vs. 10.7 (9.6, 12.0) pg/mg]; however, animals diagnosed with subclinical endometritis in experiment 2 did not differ in hair cortisoi concentrations [11.7 (9.8, 14.0). 12.2 (9.3, 15.9), 10.5 (8.1, 13.6) pg/mg for control, END. and END+CLIN, respectively]. In experiment 1, an effect of sample day was noted, where d 21 had higher cortisoi concentrations than d 42, 84, and 126. but not from d 0 for both parities. Within both experiments, a parity effect was present where multiparous animals consistently had higher cortisoi concentrations than primiparous animals. Multiparous cows that became pregnant by 100 d postpartum had lower concentrations of hair cortisoi at d 42 and 84 in milk. Lastly, other biomarkers associated with metabolic status and acute inflammation, such as glucose, β-hydroxybutyrate, haptoglobin, and ceruloplasmin, were not strongly correlated with measurements of cortisoi in hair. Overall, hair cortisoi measurements appear to be associated with clinical disorders and have a direct association with pregnancy status; however, concentrations of hair cortisoi may not be suited to differentiate situations of stress with lower magnitudes, such as the development of subclinical disease.