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Title: Influence of a prenatal stressor on ACTH-induced cortisol secretion in yearling Brahman heifers

item SCHMIDT, SARAH - Texas A&M University
item ROBERTS, MEGHAN - Texas A&M University
item PRICE, DEBORAH - Texas A&M University
item LITTLEJOHN, BRITTANI - Texas A&M University
item VANN, RHONDA - Mississippi State University
item Carroll, Jeffery - Jeff Carroll
item Sanchez, Nicole
item NEUENDORFF, DON - Texas A&M University
item LEWIS, ANDREW - Texas A&M University
item WELSH, JR., THOMAS - Texas A&M University
item RANDEL, RONALD - Texas A&M Agrilife

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 11/27/2014
Publication Date: 7/25/2014
Citation: Schmidt, S.M., Roberts, M.C., Price, D.P., Littlejohn, B.P., Vann, R.C., Carroll, J.A., Sanchez, N.C., Neuendorff, D.A., Lewis, A.W., Welsh, Jr., T.H., Randel, R.D. 2014. Influence of a prenatal stressor on ACTH-induced cortisol secretion in yearling Brahman heifers. Journal of Animal Science Supplement. 92(E-Suppl. 1):28. (Abstract #76).

Interpretive Summary:

Technical Abstract: The objective of this study was to test whether prenatal stress affects postnatal adrenocortical responsiveness to exogenous adrenocorticotropin-releasing hormone (ACTH) in calves of Brahman cows transported for 2-hour periods at 60, 80, 100, 120, and 140 days of gestation. Prenatally stressed yearling heifers (n=12) from this group and 12 Control heifers of similar body weight (208.4 +/- 4.4 kilograms) were balanced for temperament and subjected to an intravenous ACTH challenge to compare induced adrenal cortisol secretion. The subjects were fitted with jugular vein cannulas and immediately placed in stanchions for blood collection. Following a 6-hour acclimation period, porcine ACTH (0.1 international units/kilogram body wieght) was administered intravenously to each heifer. Blood samples were collected via the cannulas during the acclimation period every 30 minute and then at intervals of 15 and 30 min for 6 hours following the ACTH dose. The concentration of serum cortisol was determined by RIA. Repeated measures mixed models analysis was used to examine prenatal treatment differences over time for the full sampling period and the post-challenge period. The following variables were calculated to compare adrenal responsiveness to exogenous ACTH: peak cortisol concentration, basal cortisol concentration, time to reach peak cortisol concentration following ACTH administration, and time to return to basal cortisol concentration following ACTH administration. Cortisol concentration over time did not differ between prenatal treatment groups for either the full or post-challenge sampling periods (P = 0.12). Neither basal (6.53 +/- 1.15 vs. 5.52 +/- 1.10 nanograms/mililiter) nor peak cortisol (57.84 +/- 4.93 vs. 54.04 +/- 4.70 nanograms/mililiter) concentrations differed between the prenatally stressed and control treatment groups (P = 0.53). It appears that there is no difference on the adrenal response to ACTH challenge between prenatally stressed and control heifers. Further research is needed to determine if prenatal stress may have altered the hypothalamic or pituitary components of the hypothalamic-pituitary-adrenal axis in this group of heifers.