What does it imply when a pig oinks, squeals, or grunts? New study aims to find out.
Researchers from the University of Copenhagen, ETH Zurich, and the French National Research Institute for Agriculture, Food, and Environment captured 7,414 noises from 411 pigs in various circumstances for a study which aims to understand pig emotions.
The researchers then devised an algorithm to determine if the pigs were experiencing a happy, negative, or mixed mood.
The recordings were made in settings that commercial pigs face from birth to death, according to the University of Copenhagen. Researchers also kept track of participants’ behaviour and heart rates.
“Because of the impact of emotions on vocalisation, examination of vocal expression of emotions is increasingly being viewed as an important non-invasive approach for assessing the affective elements of animal welfare,” according to the study.
“Vocalizations of diverse animal species produced in distinct emotional situations and/or physiological conditions have been demonstrated to display specific auditory properties,” it continued.
Piglets suckle from their mothers or are reunited with family members are examples of positive events. Separation, conflicts, castration, and slaughter are examples of negative conditions.
Researchers also created simulated scenarios to elicit more complex emotions. An arena with toys or food and a comparable arena with no such stimuli were two examples of such settings. They also included several new and unusual items.
What Were The Results?
When we look at happy and bad conditions, there are clear changes in pig calls,” said Elodie Briefer, a professor at the University of Copenhagen’s biology department who co-led the study.
Pigs vocalise high-frequency noises like screams or squeals in negative condition. While low-frequency calls like barks and grunts occur when they feel both happy and negative emotions, according to the study.
“In favourable situations, the calls are much shorter, with small amplitude variations. Grunts, in particular, start out loud and progressively get quieter.
“We can classify 92 percent of the calls to the correct emotion by training an algorithm to recognize these noises.”
The majority of modern animal welfare efforts, according to the experts, are focused on physical health.
“We need someone who wants to turn the algorithm into an app. Farmers can use it to improve their animals’ welfare, including their emotions,” Briefer added.