Location: Warmwater Aquaculture Research UnitTitle: Evaluation of hair cortisol in beef cattle of divergent temperaments
|VANN, R - Mississippi State University|
|WILLARD, SCOTT - Mississippi State University|
|ROBINSON, M - Mississippi State University|
|LEWIS, A - Texas A&M University|
|WELSH, T - Texas A&M University|
|RANDEL, R - Texas A&M University|
Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 12/3/2014
Publication Date: 1/31/2015
Citation: Vann, R.C., Willard, S.T., Robinson, M., Lewis, A.W., Welsh, T.H., Randel, R.D. 2015. Evaluation of hair cortisol in beef cattle of divergent temperaments. American Society of Animal Science. P. 30.
Interpretive Summary: The objective of this research project was to evaluate the relationships among hair and serum cortisol concentrations and disposition in beef cattle. Spring born crossbred beef heifers were evaluated for temperament pre-weaning and at weaning by a variety of methods, such as pen score (1 = calm and 5 =excitable), exit velocity (how fast they exit a handling chute) and temperament score. In this study serum cortisol, a measure of physiological stress, had positive moderate correlations with temperament scores pre-weaning and at weaning, and was a better predictor of temperament assessments than hair cortisol concentrations from the varied areas that hair was collected in this study; the shoulder, rib or hip areas at weaning. These data may be used to establish predictive markers for temperament in beef cattle such that selection tools and criteria may be developed for more efficient animals based on the production-management environment in which they may be housed.
Technical Abstract: The objective of this research project was to evaluate the relationships among hair and serum cortisol concentrations and cattle disposition. Spring born (n = 101) crossbred beef heifers (7 to 8 mo. of age) were evaluated for temperament preweaning and at weaning by pen score (PS; 1 = calm and 5 = excitable), exit velocity (EV; m/sec) and temperament score [TS = (PS + EV)/2]. One experienced evaluator determined PS for all calves. In addition, calves were weighed and a blood sample collected by jugular venipucture for evaluation of serum cortisol concentrations pre-weaning and at weaning. At weaning, hair samples were collected over the shoulder, rib and hip areas (7.6 cm x 12.7 cm clipped area) for evaluation of hair cortisol concentrations. Heifers were classified as calm, intermediate or temperamental based on separation of one-half standard deviation from the mean TS. Serum concentrations of cortisol were determined by RIA. Hair samples were washed with isopropanol and dried overnight, and were ground using a Retsch mixer mill 200MM at 25 Hz for 10 min, sonicated in methanol and incubated 8 h at room temperature on a multitube vortex. The supernatant was removed and allowed to dry under a stream of atmospheric air. Samples were reconstituted with phosphate buffered saline before quantification of cortisol using Salimetrics cortisol EIA assay. Data were analyzed using PROC CORR and PROC GLM of SAS. Serum cortisol at weaning was positively correlated with TS pre-weaning r = 0.45 and at weaning r = 0.51 (P < 0.001). Serum cortisol was not significantly correlated with hair cortisol at the 3 locations (rib, hip, shoulder). Hair cortisol at the shoulder and average hair cortisol (average of rib, hip and shoulder) were positively correlated with TS at weaning only r = 0.24 (P = 0.01) and r = 0.21 (P = 0.03), respectively. Hair cortisol at the rib was positively correlated with hair cortisol at the shoulder r = 0.57 (P < 0.001) and hip r = 0.57 (P < 0.001). Hair cortisol at the shoulder was positively correlated with hair cortisol at the hip r = 0.36 (P < 0.001). Serum cortisol at weaning was greater in temperamental heifers compared with calm (P < 0.005). In this study serum cortisol had positive moderate correlations with TS pre-weaning and at weaning and was a better predictor of temperament assessment than hair cortisol concentrations from either the shoulder, rib or hip areas at weaning.