Ethological and physiological indicators of positive emotions in juvenile pigs (Sus scrofa)

The natural behavior of pigs is adapted to very complex environments and is characterized by a high proportion of exploratory behaviour. In modern, intensive husbandry systems, the behaviour pigs would show in natural environments cannot be expressed to the degree that is necessary for the animals to maintain a positive emotional state. Health and behaviour problems arise in intensive pig husbandry, leading to stress and negative emotional states in the animals. This animal welfare problem fuels growing concerns of the public. As negative emotional states, such as stress, are more intensely expressed and potentially life threatening, they are easier to study. The expression of positive emotion, even though it is expressed more subtle, is no less important. This study was therefore conducted with the objective to identify, elicit and measure behavioural and physiological indicators of positive emotion in pigs. With the ability to facilitate a positive emotional state, the welfare of pigs kept in intensive livestock production systems can be greatly improved.