Temperament and hypothalamic-pituitary-adrenal axis function are related and combine to affect growth, efficiency, carcass, and meat quality traits in Brahman steers L.M. Cafe a,b, *, D.L. Robinson a,b , D.M. Ferguson a,c , G.H. Geesink a,d , P.L. Greenwood a,b a Australian Cooperative Research Centre for Beef Genetic Technologies, University of New England, Armidale, NSW 2351, Australia b Industry & Investment NSW, Beef Industry Centre, Armidale, NSW 2351, Australia c CSIRO Livestock Industries, FD McMaster Laboratories, Armidale, NSW 2350, Australia d Department of Meat Science, University of New England, Armidale, NSW 2351, Australia Received 25 October 2010; received in revised form 17 January 2011; accepted 21 January 2011 Abstract Associations between temperament, stress physiology, and productivity were studied in yearling Brahman steers (n = 81). Steers differed in calpain system gene marker status; 41 were implanted with a hormonal growth promotant at feedlot entry. Temperament was assessed with repeated measurements of flight speed (FS) and crush score (CS) during 6 mo of backgrounding at pasture and 117 d of grain finishing. Adrenal responsiveness was assessed with ACTH challenge, with plasma samples collected immediately before and 60 min after challenge. Steers with higher FS and CS had higher prechallenge plasma cortisol, glucose, lactate, and nonesterified fatty acid concentrations. The ACTH-induced cortisol response was unrelated to FS or CS, but glucose remained higher after challenge in flightier steers. The hormonal growth promotant reduced adrenal responsiveness; tenderness genotype had no effect. When temperament assessments and cortisol concentrations before and after challenge were combined in a principal components analysis, four vectors accounting for 38%, 25%, 18%, and 9% of the variation were identified. The first vector had significant loadings on temperament and prechallenge cortisol; increasing scores were associated with increased plasma glucose, lactate, and nonesterified fatty acid and with reductions in BW and feedlot growth rates, carcass fatness, and muscle pH. The second vector loaded only on ACTH-induced cortisol response; increased scores related to increased residual feed intake, number of daily feed sessions, and meat marbling score. The third and fourth vectors had different loadings on FS and CS and appeared to identify different aspects of temperament measured by FS or CS. Fewer associations were found between the third or fourth vectors and productivity traits, possibly because of lower variance accounted for by these vectors. In conclusion, temperament was related to prechallenge cortisol but not to ACTH-induced cortisol response. Principal components analysis separated these traits into separate components, which in turn had different relations with productivity traits. The largest component of temperament was described similarly by FS and CS, but there were smaller components that these described differently. There were some temperament-related differences in the metabolic status of the steers which were not related to the variation in cortisol, suggesting involvement of the sympatho-adrenal-medullary axis in these temperament-related effects. © 2011 Elsevier Inc. All rights reserved. Keywords: Cattle; Cortisol; Crush score; Flight speed; Stress physiology; Temperament * Corresponding author. Industry & Investment NSW, Beef Industry Centre, JSF Barker Building, Trevenna Rd, Armidale, NSW 2351, Australia; Tel.: +61 2 6770 1825; fax: +61 2 6770 1830. E-mail address: linda.cafe@industry.nsw.gov.au (L.M. Cafe). Available online at www.sciencedirect.com Domestic Animal Endocrinology 40 (2011) 230 –240 www.domesticanimalendo.com 0739-7240/11/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.domaniend.2011.01.005