According to new research, cows talk to one another, expressing their emotions, both positive and negative, through individualized voices. The researchers say the findings have implications for farmers and animal welfare.
Domesticated cattle are gregarious animals, living in herds in both natural and commercial farming environments. Within these herds, they use vocalizations to communicate over short and long distances.
Alexandra Green, a Ph.D. student at The University of Sydney in Australia, is studying dairy cattle vocal communication, including its emotional content.
In a study published in the journal Scientific Reports, Green and her colleagues analyzed 333 recordings of cow vocalizations from a herd of 18 Holstein-Friesian heifers (these are black and white dairy cows that are yet to be bred and/or have not yet calved). They recorded the moos over six months in a variety of emotional contexts, both positive (during estrus and in anticipation of food) and negative (when cattle were denied access to food or during visual or physical isolation from the herd).
“The novel finding was that cattle voice individuality is stable across positive and negative contexts,” says Green.
“Cattle have vocal idiosyncrasies that are stable across contexts, similar to how individual humans can be identified by their voices irrespective of what is said.”
Green and her colleagues measured over 20 vocal features of moos, including the pitch, call duration, and amplitude, as well as nonlinear features like “roughness” of the vocalization. They found that a combination of vocal parameters was responsible for encoding individuality in cow calls.
While it was known that mother cows and their calves could communicate via individually distinct voices, this study shows that cows maintain their individual voices throughout their lives and across a herd.
Green says the purpose of these calls is to help the animals maintain contact with the herd and express excitement, arousal, engagement, or distress.
She and her colleagues hope that their research will help agricultural workers care for their animals and boost animal welfare. Knowledge of cattle individuality cues could assist farmers in tuning in to the emotional state of their animals or detect individuals in a herd that require attention.
“Farmers have been very receptive to this research,” Green says. “Recording vocalizations is non-invasive, so this is a potential way to assess animal welfare on a farm without disturbing expression of the cows’ natural behaviors.”
In the future, Green would love to see acoustic devices applied in the farming industry, perhaps taking a cue from the many studies that use passive acoustic monitors to study wildlife. She’d also like to scientifically investigate human-cow interactions on farms.
“Anecdotally, farmers claim to know a lot of information about their cattle based on their voice,” she says. “I’d love to scientifically prove this through psychoacoustic experiments, such as playing cow sounds to farmers and seeing what they can identify, such as individual animals or stressed animals.
“Novel ways of assessing welfare are particularly important for the dairy industry, where herd sizes are increasing and individual animal attention is lessening.”