WS Relationship between current temperament measures and physiological responses to handling of feedlot cattle

Abstract Text: Interest in beef cattle temperament has increased due to growing consumer awareness of animal welfare. Researchers have defined temperament as behavioral responses to a perceived stressor. Subjective chute scoring has been used by many researchers for temperament, however, the subjectivity and associated variability among observers has been questioned. The most practical objective method of assessing temperament is exit velocity. Corresponding chute side measures to physiological markers is important. Faster exit velocities have been related to both increased cortisol and increased plasma lactate. The objectives of this study were to compare temperament differences between feedlot steers and heifers and to confirm chute side measures relationship to physiological responses to stress. Body temperature, serum and plasma lactate, serum glucose, salivary and serum cortisol concentrations were measured on mixed breed and sex feedlot cattle (n = 197). Fast, medium, and slow classifications were developed from exit velocities. Plasma lactate was significantly different between all classes. Sex had a significant effect on exit velocity and physiological measures. Heifers had higher exit velocities (P = 0.003), plasma lactate concentrations (P = 0.03), and cortisol concentrations (P = 0.001). Simple correlations among these variables indicated body temperature (heifers r = 0.44, P < 0.0001; steers 0.45 P < 0.0001), plasma lactate (heifers r = 0.52 P < 0.0001; steers r = 0.63 P < 0.0001), serum lactate (heifers r = 0.53 P < 0.001; steers r = 0.59 P < 0.001) and glucose (heifers r = 0.54 P < 0.001; steers r = 0.32 P<0.003) were all correlated to exit velocity in both steers and heifers. Cortisol measures were not correlated to exit velocity in steers but were in heifers. Linear models constructed and evaluated using Akaike information criterion indicated that plasma lactate in combination with body temperature were strong candidates to predict exit velocity. Using the discriminate function analysis, the model categorized fast and slow classifications 69.23% and 61.54% respectively, indicating that in combination with exit velocity simple objective chute side measures of body temperature and plasma lactate can potentially increase accuracy of temperament identification.

Keywords: Cortisol, Lactate, Temperament