|Carroll, Jeffery - Jeff Carroll|
Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/20/2005
Publication Date: 7/9/2006
Citation: Curley, K.O., Lyons, J., Brown, M.S., Lawrence, T.E., Carroll, J.A., Vann, R.C., Willard, S.T., Welsh, Jr., T.H., Randel, R.D. 2006. Influence of breed type and temperament on anatomic and endocrinologic parameters of the bovine hypothalamic-pituitary-adrenal (HPA) axis [abstract]. Journal of Animal Science. 84:353(Suppl. 1). Abstract #W170.
Technical Abstract: Temperament has been shown to affect bovine adrenal cortical and medullary stress responses. The biological mechanisms responsible for increased secretion of glucocorticoids and catecholamines in beef cattle with poor temperament remain undetermined. The objective of this study was to compare anatomic and endocrinologic paramaters of the hypothalamic-pituitary-adrenal (HPA) axis within and across temperament and breed type. Exit velocity (EV), the rate at which the cattle exited the squeeze chute and traversed a fixed distance (1.83 m), was used to identify the 10 calmest (C) and 10 most temperamental (T) weaned calves from both Brahman (B) and Angus (A) herds. The steers were fed to a similar rib fat thickness at a feedyard in Canyon, TX. Blood samples were obtained via coccygeal venipuncture on d113 of the feeding period. Serum concentrations of cortisol (CS), and plasma concentrations of epinephrine (EPI) and norepinephrine (NOR) were determined by RIA and EIA, respectively. Temperament influenced CS (P = 0.001; C = 16.98 + or - 1.8, T = 31.07 + or - 3.7 ng/mL), EPI (P = 0.025; C = 136.71 + or - 17.5, T = 490 + or - 159.2 pg/mL), and NOR (P = 0.044; C = 307.23 + or - 22.9, T = 1119.83 + or - 427.6 pg/mL). However, no effects of breed or breed by temperament interaction were observed for these endocrine parameters. At the time of harvest, left adrenal glands and pituitaries were collected so that adrenal cross-sectional areas and pituitary weights could be analyzed. There were no effects of temperament or breed by temperament interactions observed for the anatomical parameters. However, breed influenced adrenal area (P = 0.022; A = 121.37 + or - 4.4, B = 106.53 + or - 4.8 mm2) as well as cortical area (P = 0.043; A = 91.06 + or - 3.1, B = 80.53 + or - 4.2 mm2). Concerning the pituitary gland, breed influenced (P < 0.001) both whole pituitary weight (A = 2.11 + or - 0.1, B = 1.27 + or - 0.04 g) and anterior pituitary weight (A = 1.65 + or - 0.07, B = 0.97 + or - 0.07 g). Breed type influenced anatomic parameters of the HPA axis, whereas temperament influenced endocrinologic function of the adrenal cortex and medulla of beef steers.