The body language of dairy calves : investigating emotions through ear posture, tail posture, and stepping behaviour

Abstract: While improving animal welfare has become an important task in both the agricultural and scientific community, increased knowledge on positive emotions in animals and on methods of assessing welfare are needed in order to continue to move forward in this endeavour. Through understanding the connection between the body language of animals and their emotional state, further progress can be made. This study assessed the ear postures, tail postures, and stepping behaviour of 16 dairy calves when exposed to four experimental stimuli expected to elicit emotional states of varying valence and arousal levels, and a control. The stimuli included feeding of concentrates, gentle stroking, the absence of social interactions/stimuli, and spraying with water. Results were then compared to body posture predictions based on previous research where ear and tail postures of dairy cows during different activities were analyzed and plotted onto an arousal/valence framework i.e. the dimensional model of core affect. Predictions for the ear postures backward, asymmetric right, and asymmetric left during a positive, low arousal emotional state showed a trend of being supported. The backward and forward ear postures of calves may be more influenced by changes in arousal, while the asymmetric right ear indicated an emotional state of positive, high arousal. The highest occurrence of stepping behaviour was displayed during the boredom stimulus, indicating that this treatment was perceived as being of high arousal by the calves, rather than low arousal as intended. Overall tail activity of the calves was low. No tail predictions were confirmed, however, a new posture of a tucked tail seemed to be representative of a negative, high arousal emotional state. Further research is needed to determine the role that age, experience, and stimuli play in regards to an animal’s emotional state and to determine the validity of using the dimensional model of core affect to predict the body language and emotional state of animals in varying situations.