Anxious to make progress in animal welfare, European researchers have developed a tool to decipher the feelings pigs express in their various growls.
Across Switzerland, Denmark, Norway, France and the Czech Republic, biologists studied more than 7,000 recordings of 411 pigs, from the brief screams of satisfaction at suckling to the desperate cries of slaughter, before classifying them into 19 different categories.
“We show that it is possible to determine the emotions of pigs based on their vocalizations”explains project manager Elodie Briefer, lecturer at the University of Copenhagen.
The study, published in the journal Natureoffers a new way to improve animal welfare with a tool to categorize an emotion by the sound produced, according to the researcher.
“We also use a machine learning algorithm […] which produces and trains a spectrogram to recognize negative and positive contexts. If the percentage of negative noises increases, the farmer knows that something is probably wrong and can start checking the pigs.”
Once developed, this new type of monitoring will enable farmers, who only have physical welfare tools, to ensure the mental health of their animals.
For the Danish Council of Agriculture – the Scandinavian country is home to 13.2 million pigs, a European record of more than 2 pigs per capita – the implications of the research are promising. “this concept” […] could, among other things, be a useful tool in monitoring the health and welfare of pigs”said Trine Vig, a spokesman for the Council.
According to Ms. Briefer, “we achieve an accuracy of 92% in classifying the valence, i.e. determining whether the call is negative or positive, and 82% in classifying the actual context in which the sounds were produced”†
According to the findings of the study, positive feelings are expressed in short sounds, while negative thoughts are usually expressed extensively. But why dwell on the pig instead of the veal or rabbit? For the authors of the study, the pig, which is known for its highly varied squeaks and sounds, was the perfect stallion.
“They are very vocal, which makes studying them easy […] they produce vocalizations all the time. Even in low intensity situations they continue to vocalize”emphasizes the university.