Forbes, T. D. A.

Holloway, J. W.

Koch, J. W.

Lippke, H.

Lunt, D. K.

Miller, R. K.

Randel, R. D.

Riley, D. G.

Rouquette, F. M., Jr.

Sanders, D.

Welsh, T. H., Jr.

English

Texas A&M University

Influence of Bos Taurus and Bos Indicus Breedtype on Production of Cortisol

Texas A&amp;M Repository

    PUBLICATIONS 2000 INFLUENCE OF BOS TAURUS AND BOS INDlCUS BREEDTYPE ONPRODUCTION OF CORTISOL1. W. Kochl.\ T. H. Welsh!, R. K. Millerl, J. O. Sandersl, D. G. Rileyl, D. K. Lunf,J. W. Holloway3, T.D.A. Forbes3, H. Lippke3, F. M. Rouquette, Jr.4 and R. D. Randel4Texas Agricultural Experiment Station. ICollege Station. 1McGregor. JUvalde and~Overton. Background. The genetic influence on the physiological response to stress is not well .understood. Recent studies in humans have shown that racial differences exist in the function ofthehypothalamic-pituitary-adrenal (HPA) axis and that some functional aspects of the HPA axis maybe heritable. Earlier studies in cattle showed breed differences in dominance rank within the herdand temperament in a squeeze chute. Breed differences were also reported for baseline and ACTH-stimulated plasma cortisol concentrations in beefcalves. We have noted that adrenal gland weight,adrenal cortical area and plasma concentration of ACTH and cortisol are greater for Bos taurus(Angus) relative to Bos indicus (Brahman) cattle. For instance, plasma concentration ofcortisol washigher for Angus (44.9 ±2.3 nglml) than for Brahman (35.5 ±3.4 ng/ml) steers. Computer-assistedimage analysis of adrenal gland morphology revealed that Angus steers had 13% greater corticalarea than Brahman steers. These studies imply that genotype and heredity influence the stressresponse; however, they do not fully explain the mechanisms for these genotypic effects.Cortisol is a steroid hormone produced by the outer zones ofthe adrenal gland in responseto environmental or managerial or psychological stimuli. In "addition to its role in responding tostressors and mobilizing energy, cortisol can be anti-inflammatory. However, cortisol can also becatabolic and diminsh protein production. It is of interest to develop systems to assess or predict ananimal's stress responsiveness and relate adrenal gland cortisol prodution to production and carcasstraits.Research Objective and Method. The objective of this experiment was to determine ifdifferences exist in proportional response (fold increase) of plasm~cortisol following an injectionof adrenocorticotropin; ACTH, (0.1 IUlkg ofbodyweight). Full blood Bos taurus (BT, n =58), 3/4Bos taurus - 1/4 Bos indicus (.25 BI, n = 137), 1/2 Bos taurus - 1/2 Bos indicus (.5 BI, n = 96), andfull blood Brahman (BI, n = 24) stocker steers and heifers owned by the Texas AgriculturalExperiment Station were utilized for this study. A blood sample was taken via tail venipuncture andfollowed immediately by an intravenous injection of ACTH into the jugular vein. A second bloodsample was taken via tail venipuncture 30 minutes following ACTH injection.25Research Findings. There were no differences (p > .10) in proportional response ofcortisol(PR) between steers and heifers within breedtype. The PR was higher (p ::s .0028) in the BT cattlecompared to the .50 BI cattle and the BI cattle (2.48 ± 0.20 vs. 1.69 ± 0.15; 1.37 ± 0.31,respectively). There was no difference (p =.31) in PR between the BT cattle and .25 BI cattle (2.48± 0.20 vs. 2.24 ±0.13, respectively). The PR was higher (P::S .010) in the .25 BI cattle comparedto the .50 BI cattle and BI cattle (2.24 ± 0.13 vs. 1.69 ± 0.15; 1.37 ± 0.31, respectively). Theproportional response was not different (p =.36) between the .50 BI cattle and the BI 'Cattle (1.69±0.15 vs. 1.37 ±0.31, respectively). These results indicate animals ofvarious percentages ofBosindicus and Bos taurus breedtype respond differently in production of cortisol after exogenousACTH.The ACTH challenge protocol will be used again.at the end efthe grazing period and neartermination ofthe feedlot period. Adrenal responsiveness will be compared among breed types andits relationship, if any, to carcass traits will be determinedApplication. An animal's genetic make-up may affect its susceptibility and(or) resistanceto stressors. A certain breedtype or individual may possess traits that reduce (enhance) the negativeconsequences of stress and allow for greater (less) production efficiency. Additional studies mayprovide a more complete understanding of how genotype controls these traits which could lead tomethods of selection for animals that are stress resistant.26

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Influence of Bos Taurus and Bos Indicus Breedtype on Production of Cortisol

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Texas A&M University

Texas A&M Repository

Influence of Bos Taurus and Bos Indicus Breedtype on Production of Cortisol

Abstract

Similar works

Full text

Available Versions

Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository