Relationships between temperament and transportation with rectal temperature and serum concentrations of cortisol and epinephrine in bulls

This study investigated whether temperament influences rectal temperature and serum concentrations of cortisol and epinephrine in response to transportation. 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. Whole blood was collected pre- and post-transport, and rectal temperature recording devices were inserted pre-transport for continual collection of rectal temperature during transport. Bulls were transported in a trailer 770 km from Overton, TX (32.27 N, − 94.98 W, 153 m altitude) to New Deal, TX (33.74 N, − 101.84 W, 1006 m altitude). Serum cortisol and plasma epinephrine concentrations were determined. Prior to transportation (0 min) Temperamental bulls had greater rectal temperature than Calm or Intermediate bulls (P < 0.05). Rectal temperature peaked within 30 min after the onset of transportation with Temperamental bulls having greater peak rectal temperatures than Calm or Intermediate bulls (P < 0.05). The lowest mean rectal temperature was reached 400 min after the onset of transportation with Calm bulls having lower mean rectal temperatures than Intermediate or Temperamental bulls (P < 0.05). Prior to transportation Temperamental bulls had greater cortisol concentrations than Calm bulls (P < 0.05). Temperamental bulls had greater concentrations of epinephrine prior to transportation than Calm or Intermediate bulls (P < 0.05). Temperamental bulls also had greater concentrations of cortisol and epinephrine post-transportation than Calm bulls (P < 0.05). Maximum and minimum rectal temperature were positively correlated (r = 0.73; P < 0.01). There was a positive correlation between EV and maximum rectal temperature (r = 0.62; P = 0.01), and a trend for EV to be positively correlated with minimum rectal temperature (r = 0.43; P = 0.10). Epinephrine tended to be positively correlated with maximum rectal temperature (r = 0.46; P = 0.06). Both cortisol (pre-transportation r = 0.55; P = 0.02) and epinephrine (pre- and post-transportation (r = 0.64; P < 0.01 and r = 0.59; P < 0.01, respectively) were positively correlated with EV. In summary, temperament was predictive of 1) changes in rectal temperature due to transportation and 2) circulating concentrations of cortisol and epinephrine before and after transportation.