title: Relationship of concentrations of cortisol in hair with health, biomarkers in blood, and reproductive status in dairy cows.
abstract: Hair cortisol has been used to measure chronic stress in dairy cows as it offers the advantage of being noninvasive, fast, and able to indicate levels of cortisol over long periods. The aim of this study was to determine the associations between hair cortisol with clinical disorders, reproductive status, and the development of subclinical endometritis in dairy cows. Furthermore, we aimed to determine the association between hair cortisol concentrations and blood markers associated with metabolic status and acute inflammation. In experiment 1, cows (n=64) were hair sampled every 3wk from the tail switch beginning at calving (d 0) until d 126 for cortisol analysis; blood samples were collected every 3wk from d 0 until 42 for β-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±3d in milk. At the same time, animals were hair sampled for cortisol analysis and blood sampled for haptoglobin and ceruloplasmin analysis. Health records were recorded throughout both experimental periods. Animals with clinical disease presented higher cortisol 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 cortisol 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 cortisol 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 cortisol concentrations than primiparous animals. Multiparous cows that became pregnant by 100d postpartum had lower concentrations of hair cortisol 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 cortisol in hair. Overall, hair cortisol measurements appear to be associated with clinical disorders and have a direct association with pregnancy status; however, concentrations of hair cortisol may not be suited to differentiate situations of stress with lower magnitudes, such as the development of subclinical disease.
authors.affiliation: Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada.
authors.forename: Tracy A
authors.initials: TA
authors.lastname: Burnett
authors.affiliation: Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada.
authors.forename: Augusto M L
authors.initials: AM
authors.lastname: Madureira
authors.affiliation: Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada.
authors.forename: Bruna F
authors.initials: BF
authors.lastname: Silper
authors.affiliation: College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran 91775-1163.
authors.forename: Abdolmansour
authors.initials: A
authors.lastname: Tahmasbi
authors.affiliation: Agriculture & Agri-Food Canada, Agassiz, BC, V0M 1A0 Canada.
authors.forename: Audrey
authors.initials: A
authors.lastname: Nadalin
authors.affiliation: Agriculture & Agri-Food Canada, Agassiz, BC, V0M 1A0 Canada.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Veira
authors.affiliation: Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada. Electronic address: ronaldo.cerri@ubc.ca.
authors.forename: Ronaldo L A
authors.initials: RL
authors.lastname: Cerri
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D015415:Biomarkers; D002417:Cattle / Q000097:blood / Q000502:physiology*; D004716:Endometritis / Q000662:veterinary; D005260:Female; D006197:Hair / Q000737:chemistry*; D006854:Hydrocortisone / Q000097:blood* / Q000737:chemistry*; D008892:Milk / Q000378:metabolism; D049590:Postpartum Period; D011247:Pregnancy; D012098:Reproduction / Q000502:physiology*; D013312:Stress, Physiological
chemical_list: D015415:Biomarkers; D020155:3-Hydroxybutyric Acid; D006854:Hydrocortisone
keywords: chronic stress; dairy cattle; disease; hair cortisol