Livestock Emotions, Vocalisations and Positive Welfare

Emotions allow appropriate behavioural decisions in response to environmental information. They can be characterized in two dimensions: arousal (excitation) and valence (positive or negative). Understanding and measuring positive emotions in animals is often more challenging than negative ones, but is nevertheless important for better welfare. The emotions that animals experience also affect the structure of the vocalisations they produce (e.g. goats) or the types of vocalisations (e.g. chickens). Thus, we can potentially use vocalisations to identify positive or negative welfare states.
First, I will outline how we have identified indicators of positive emotions in goats. After positive treatment, goats produced vocalisations in which pitch was more stable. Further, in positive states compared with negative ones, goats had their ears oriented backwards less often and spent more time with their tails up.
Chickens produce a wide range of vocalisation types, but utter distress vocalisations when they are stressed. The output of distress vocalisations produced in commercial broiler flocks (e.g. 26,000 birds) may be used as an “iceberg indicator” of welfare, because it is linked to growth and mortality. However, to monitor distress calls from large numbers of birds, it is necessary to automate their identification. Recently, we have developed an algorithm that correctly identifies 97% of chicken distress vocalisations. However, our end goal is not to simply identify distress vocalisations, but to create farm conditions in which chickens can live with less stress. Overall, livestock welfare indicators will allow us to improve husbandry, by minimising negative states and promoting positive ones.