|Welsh Jr., Tom - Texas Agrilife Research|
|Burdick, Nicole - Texas Agrilife Research|
|Curley Jr., Kevin - Texas Agrilife Research|
|Agado, Brian - Texas Agrilife Research|
|Willard, Scott - Mississippi State University|
|Carroll, Jeffery - Jeff Carroll|
|Vann, Rhonda - Mississippi State University|
|Randel, Ron - Texas Agrilife Research|
Submitted to: Endocrine Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/27/2009
Publication Date: 6/10/2009
Citation: Welsh Jr., T., Burdick, N., Curley Jr., K., Agado, B., Willard, S., Carroll, J.A., Vann, R., Randel, R. 2009. Influence of gender and breed type on basal and induced secretion of cortisol in cattle [abstract]. In: Proceedings of the Endocrine Society's 91st Annual Meeting, June 10-13, 2009, Washington, D.C. Abstract #P2-640.
Technical Abstract: To test the hypothesis that gender and breed type affect cortisol secretion, Angus (Bos taurus) and Brahman (Bos indicus) bulls (intact males), steers (castrate males), and heifers (intact females) were studied. Jugular venipuncture samples were taken from 900 cattle at: 28 days before weaning; weaning (7 months of age); 28 and 56 days after weaning; and 1 year of age to assess basal cortisol secretion. Blood samples were taken via jugular vein catheter from yearling Brahman bulls and heifers to assess cortisol secretion before and after i.v. injection of ACTH (.10 IU/kg BW i.v.; n=12 bulls and n=12 heifers) or lipopolysaccharide (LPS, .25 micrograms/kg BW; n=6 bulls and n=6 heifers). Jugular blood samples were taken from Angus (n=20) and Brahman (n=20) feedlot steers prior to harvest when pituitary and adrenal glands were processed. Serum cortisol concentration was determined by RIA. Data were analyzed by ANOVA for repeated measures. For both breeds, cortisol concentration was lower (P<0.01) in bulls relative to steers and heifers which did not differ from each other. Angus bulls, steers, and heifers had greater (P<0.01) cortisol concentration than did their Brahman counterparts. For the ACTH-treated yearling cattle, basal cortisol was lower (P<0.01) in bulls (5.8 0.7 ng/ml) than heifers (14.9 2.2 ng/ml). Cortisol concentration at 30-min post ACTH was higher (P<0.01) in heifers (60 4 ng/ml) than bulls (33.6 3.3 ng/ml). For the LPS-treated yearling cattle, heifers tended (P=0.10) to have greater basal cortisol than bulls whereas cortisol was greater (P<0.01) in heifers than bulls by 2 hours post-LPS. For feedlot cattle, cortisol concentration did not differ between Angus (25.8 0.4 ng/ml) and Brahman (21.9 0.4 ng/ml) steers although Angus steers had heavier anterior pituitary and adrenal gland weights and a greater adrenocortical area (P<0.01). These observations support the concept that adrenocortical function is influenced by breed type and that sexual dimorphism in basal and induced cortisol secretion can occur across genetic strains or breeds.