Understanding how animals express emotions during mildly positive or negative situations could lead to their better welfare, researchers say.
For this, the team from Queen Mary University of London (QMUL) in Britain looked at how goats express subtle positive emotions.
They found that goats were more likely to point their ears forward and keep their tail up when they were in a positive state as well as producing more stable calls (less varied in frequency).
It is often relatively easy to identify negative emotions in animals but we know little about how they show that they are experiencing positive states.
"Subtle hints from goats like small changes in their calls, their heart rate or the position of their ears tell us about what state it is in and could indicate whether their environment is good for their welfare or not," said lead researcher Alan McElligott from QMUL.
Given an increasing desire among consumers to ensure that farm animals have the best possible welfare, the research could pave the way for changes in how animals are looked after.
The research was published in the journal Animal Behaviour.