A Cow's Moo Can Reveal How They Are Feeling

The vocal tics of a cow's moo can reveal their feelings, expressing a variety of emotions from distress to excitement, according to a new study.

Research published in Scientific Reports suggests cattle talk to one another, communicating their emotions, positive and negative, through individualized voice cues.

The study was led by Alexandra Green, a PhD student at The University of Sydney, who monitored voice calls in a herd of 18 Holstein-Friesian heifers for five months.

Domesticated cattle such as Holstein-Friesian heifers are "gregarious" creatures, according to the researchers, and use vocalizations as a means of mediation within the group.

"Domesticated cattle are highly gregarious, residing in herds in both natural and commercial farming environment," they wrote.

"Within these herds, interactions over short and long distances are mediated by vocalisations."

Green and colleagues studied 333 recordings of cow vocalizations. These included positive calls made during oestrus (a period of sexual receptivity in females, when ovulation occurs) or in anticipation of feed. They also included negative calls made when they were denied feed or isolated from the herd.

The researchers identified two broad call types—a low-frequency nasal call for close-contact or times of low distress and a high-frequency call from the mouth for distant communication and times of high arousal.

The purpose of these calls, they say, is to allow each of the individual cows to maintain contact with the others. It enables them to express their emotions, whether they happen to be feeling excited, aroused, engaged or distressed.

Researchers are finding more and more evidence of vocal calls like these across species—for example, in pigs, horses and wild boar. But while it was known that female cows and their calves could communicate via individualized voicing, this study suggests they maintain individualized voicing throughout their lifetime.

"Cows are gregarious, social animals. In one sense it isn't surprising they assert their individual identity throughout their life and not just during mother-calf imprinting," Green said in a statement.

"But this is the first time we have been able to analyse voice to have conclusive evidence of this trait."

The team hopes the news will help agricultural workers care for their livestock and boost animal welfare by integrating some of the findings into their daily practices.

"We hope that through gaining knowledge of these vocalisations, farmers will be able to tune into the emotional state of their cattle," said Green.

The underpinnings of human language is one of biology's biggest mysteries, but scientists are increasingly finding that animals from elephants to naked mole rats engage in conversations of sorts, taking turns to communicate.

Holstein cows
Holstein cows stand in a field on March 15, 2019, in Mauves-sur-Loire, nortwestern France. New research suggests cows "talk" about their feelings. CHARLY TRIBALLEAU/AFP/Getty