We can now decode the emotions of pigs. Thanks to 7,414 acoustic recordings collected throughout the lives of 411 pigs, from birth to death, an international team of scientists has been the first in the world to translate the grunting of pigs into real emotions through a large number of conditions and life stages (including the slaughter phase).
The research, led by the University of Copenhagen, ETH Zurich and France’s National Research Institute for Agriculture, Food and the Environment (INRAE), can be used to monitor the mental health of these animals and improve their well-being in the wild. future. Their findings have been published in the journal Scientific Reports.
It is based on a thoroughly trained algorithm to calculate the mental well-being of pigs. The algorithm could potentially be used to build an app for pig farmers that detects whether animals are okay, just by the noise they’re making.
The researchers say the algorithm can decode whether a given pig is experiencing a positive emotion (‘happy’ or ‘excited’), a negative emotion (‘scared’ or ‘stressed’) or something in between. Positive situations included, for example, when piglets nurse their mothers or when they are reunited with their family after being separated. Emotionally negative situations included loss of lactation, brief social isolation, piglet fights, crushing of piglets by the mother, castration, and handling and waiting at the slaughterhouse.
In experimental barns, the researchers also created various mock scenarios for the pigs, designed to evoke more nuanced emotions in the middle of the spectrum (such as a sand play area or a food area). They also placed new and unfamiliar objects for the pigs to interact with. They monitored and recorded the animals’ grunting, behavior and heart rate whenever possible.
The training of the algorithm resulted in the possibility of classifying 92% of the calls or growls with the correct emotion that the pigs felt. It confirmed what happened in previous investigations, registering more high-frequency calls (such as yelling and screaming) in negative situations.
“There are clear differences in pig calls when we look at positive and negative situations. In positive situations, the calls are much shorter, with smaller fluctuations in amplitude. Grunts, more specifically, start out high and gradually drop in frequency ,” the authors clarify.
A way to measure animal welfare
“With this study, we show that the sounds of animals offer a great understanding of their emotions. We also show that an algorithm can be used to decode and understand the emotions of pigs, which is an important step towards improving animal welfare.” for livestock ,” explained Elodie Briefer from the University of Copenhagen Department of Biology at the University of Copenhagen and co-author of the study.
The researchers hope their algorithm could pave the way for a new platform for farmers to monitor the psychological well-being of their animals, but this same method could be used to better understand the emotions of other mammals.
Referencia: Briefer, E.F., Sypherd, C.C.R., Linhart, P. et al. Classification of pig calls produced from birth to slaughter according to their emotional valence and context of production. Scientific Reports 12, 3409 (2022). DOI: https://doi.org/10.1038/s41598-022-07174-8
