Location: Livestock Issues Research
Title: Temperament dictates endotoxin-induced metabolic changes in Brahman bulls Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 15, 2011
Publication Date: August 24, 2011
Citation: Carroll, J.A., Sanchez, N.C., Randel, R.D., Vann, R.C., Welsh Jr, T.H. 2011. Temperament dictates endotoxin-induced metabolic changes in Brahman bulls [abstract]. Proceedings of the 7th International Conference on Farm Animal Endocrinology, August 24-27, 2011, Bern, Switzerland. p. 9-10. Abstract #2. Technical Abstract: We previously reported that animal temperament influences the rectal temperature response, sickness behavior scores, serum concentrations of epinephrine (Burdick et al., 2011; Innate Immunity), and serum cytokine concentrations (Hulbert et al., 2009; J. Anim. Sci. 86 (Suppl 2):527) following a provocative endotoxin (i.e., lipopolysaccharide, LPS) challenge in Brahman bulls. We now describe the influence of temperament on alterations in peripheral blood concentrations of key metabolic parameters (i.e., insulin, glucose, and non-esterified fatty acids (NEFA)) that respond to an LPS challenge. Brahman bulls were selected based on temperament score (average of exit velocity - EV, and pen score - PS) measured 28 days prior to weaning with the 8 most Calm (0.89 ± 0.15 EV and 1.00 ± 0.00 PS), 8 most Temperamental (3.70 ± 0.29 EV and 4.88 ± 0.13 PS), and the 8 Intermediate (1.59 ± 0.12 EV and 2.25 ± 0.16 PS) selected from a pool of 60 bulls. At 10 mo of age, the selected bulls were fitted with indwelling jugular catheters for serial blood collection to evaluate metabolic parameters before and after LPS administration (0.5 micrograms/kg) approximately 24 hr before the beginning of the study. Blood samples were collected at 30-min intervals from -2 to 8 hr and at 24 hr relative to the LPS challenge at time 0. Prior to LPS administration, glucose concentration did not differ among temperament groups (P > 0.10). However, serum concentrations of insulin were lower (P = 0.02) and NEFA greater (P < 0.001) in the Temperamental bulls compared to Calm and Intermediate bulls prior to LPS exposure. Post-LPS glucose concentrations increased in Calm and Intermediate bulls (P < 0.001) within 30 min of the challenge, peaking at 1 hr and .5 hr, respectively. Serum concentration of glucose did not increase following LPS exposure in the Temperamental bulls (P > 0.21). Glucose concentration decreased below baseline at 2.5 hr in Intermediate and Temperamental bulls and at 3.5 hr in Calm bulls. By 24 hr post-LPS, glucose concentration had returned to baseline. Post-LPS insulin concentration increased, peaking at 2 hr in all bulls. Peak insulin concentration was 2.5 fold greater in Calm than Intermediate and Temperamental bulls. Insulin concentration returned to baseline by 3 hr in Intermediate and Temperamental bulls and by 4 hr in Calm bulls. Post-LPS NEFA concentration fluctuated throughout the sampling period, with Temperamental bulls maintaining greater NEFA concentration (P < 0.001) compared to Calm and Intermediate bulls. Collectively, our data demonstrate that temperament is related to the endocrine, behavioral, and physiologic responses of pre-pubertal Brahman bulls following a provocative endotoxin challenge. Additionally, these data suggest that Temperamental bulls utilize the more readily available energy source (i.e., NEFA) than Calm and Intermediate bulls (who favor glucose) in response to an LPS challenge. Utilization of NEFA rather than glucose may be more advantageous, as it appears to provide sufficient energy required for the immunological response without the need to mobilize glucose and activate insulin secretion, which could result in a detrimental hypoglycemic state.