WE CAN NOW decode pigs’ emotions. Using thousands of acoustic recordings gathered throughout the lives of pigs, an international team of researchers is the first in the world to translate pig grunts into actual emotions.

Researchers recorded 7,414 sounds from 411 pigs in different scenarios, from birth to death. A machine learning algorithm was trained to decode whether pig calls can be classified as a function of positive or negative emotions.

With this study, it has been demonstrated that animal sounds provide great insight into their emotions. It also shows that an algorithm can be used to decode and understand the emotions of pigs, which is an important step towards improved animal welfare for livestock.

The researchers recorded pig sounds in both commercial and experimental scenarios, which based on the behavior of the pigs, are either associated with a positive and negative emotion. Positive situations included, for example, those when piglets suckle from their mothers or when they are united with their family after being separated. The emotionally negative situations included, among others, separation, fights between piglets, castration and slaughter.

In experimental areas, the researchers also created various mock scenarios for the pigs, designed to evoke more nuanced emotions in the middle of the spectrum. These included an arena with toys or food and a corresponding arena without any stimuli. The researchers also placed new and unfamiliar objects in the arena for the pigs to interact with. Along the way, the pigs’ calls, behavior and heart rates were monitored and recorded when possible.

The researchers then analyzed the audio recordings to see if there was a pattern in the sounds as a function of the emotions, and if they could discern the positive situations and emotions from the negative ones. As already shown in previous research, the researchers collected more high-frequency calls (such as screams and squeals) in negative situations. At the same time, low-frequency calls (such as barks and grunts) occurred both in situations where the pigs experienced positive or negative emotions.

The situations between the extremes were particularly interesting. With an even more thorough analysis of the sound files, the researchers found a new pattern that revealed what the pigs experienced in certain situations in even greater detail.

The study of animal emotions is a relatively new field that has come about over the last 20 years. Today, it is widely accepted that the mental health of livestock is important for their overall well-being. Nevertheless, today’s animal welfare focuses primarily on the physical health of livestock. Indeed, several systems exist that can automatically monitor an animal’s physical health for a farmer. Will this kind of research catch on in the third world? Not here yet, since we are still busy catching crooks and cash for research funds. By Manny Palomar, PhD (EV Mail January 16-22, 2023 issue)