Evaluation of pulsatility index and diameter of the jugular vein and superficial body temperature as physiological indices of temperament in weaned beef calves: Relationship with serum cortisol concentrations, rectal temperature, and sex

Abstract

The relationship between temperament, pulsatility index and diameter of the jugular vein, and body temperature was assessed in Angus crossbred calves (262±24.9 days old). Temperament scores were used to classify calves as calm (n=31), intermediate (n=32), or temperamental (n=28). Blood samples were collected for serum cortisol concentration analysis. Rectal, skin and hair coat temperatures were also recorded. The pulsatility index and luminal diameter corrected by BW (diameter) of the right jugular vein were measured via Doppler and B-mode ultrasound, respectively. Temperament and sex groups [heifers (n=35) and steers (n=44)] were compared. Temperament and sex did not interact to affect any of the studied variables. Cortisol (4.05±0.30 and 2.97±0.18μg/dl; P=0.016) and rectal temperature (39.26±0.13 and 38.87±0.09°C; P=0.012) were greater in temperamental than in calm calves, respectively. Hair temperature was greater in temperamental than in calm calves (26.07±0.52 and 24.71±0.60°C, respectively; P=0.052). Temperamental and calm calves did not differ in skin temperature (33.61±0.45 and 33.29±0.49°C, respectively; P=0.837) or jugular vein diameter (0.052±0.002 and 0.052±0.002mm/kg, respectively; P=0.204). Temperamental calves tended to have greater pulsatility index values than calm calves (1.97±0.22 and 1.67±0.11, respectively; P=0.095). No differences were observed in cortisol (3.88±0.27 and 3.36±0.21μg/dl; P=0.104) or skin temperature (33.60±0.39 and 33.66±0.43°C; P=0.905) between heifers and steers, respectively. Heifers had greater rectal (39.22±0.10 and 38.84±0.08°C; P=0.002) and tended to have greater hair temperatures (26.91±0.57 and 25.66±0.49°C; P=0.093) than steers, respectively. However, rectal temperature was not associated to skin temperature (P=0.123), pulsatility index (P=0.719), or diameter (P=0.650). Nor was cortisol related to skin temperature (P=0.710), pulsatility index (P=0.266) or diameter (P=0.548). Therefore, under the conditions existent in the present study, rectal temperature and cortisol were able to reflect physiological differences associated with temperament in beef cattle whereas the superficial temperatures and the pulsatility index and diameter of the jugular vein did not. Arterial hemodynamic (i.e., carotids) and other superficial temperature recording methods may need to be evaluated in future studies.