Cows Get Moooody During Puberty, Too

A new study has found that bovine personalities are less predictable when cows reach sexual maturity

The forces driving the cows' personality fluctuations are likely the same bodily changes that make human teenagers a handful for their parents. Avalon_Studio/iStock

For humans, it’s practically a rite of passage: We hit puberty and suddenly transform from happy-go-lucky children to restless, emotionally unpredictable teenagers. But we may not be the only animals to experience such changes during this phase of life. According to a new study published in Royal Society Open Science, adolescent cows get moody (or “moooody,” if you will), too.

In recent years, there has been increased interest in the emotional lives of farm animals, particularly as the treatment of these creatures within the mass farming system has fallen under scrutiny. Studies typically gauge animals’ personalities by placing them in new situations and seeing how they respond. Cows, research has shown, tend to have relatively stable reactions as calves and adults. But “no work to our knowledge has investigated the … stability of personality traits of dairy cattle from an early age to adulthood,” a team of scientists from the University of British Columbia write in the new study.

Hoping to shed new light on cow development, the researchers studied groups of Holstein dairy cattle across major life phases, from the period before they were weaned to the period of lactation after the confirmation of a second pregnancy. During each phase, the cows were subjected to personality tests that allowed researchers to observe the animals’ reactions to a new environment, person and object.

“Different individuals will react in different ways,” explains senior author Marina von Keyserlingk, a professor at UBC’s Animal Welfare Program. “For instance, some calves and cows will immediately approach and investigate the object or human, or explore the new environment, while others will never touch the object or human and stand still for the duration of the test.”

Von Keyserlingk tells Hina Imam of the Globe and Mail that the bovines’ responses were interpreted as reflecting two personality traits: “bold” (assertive) or “exploratory” (more reserved and shy). During the early period of their lives (from birth to around three months of age) and during later development (from one to two-and-a-half years of age), the cows consistently displayed bold or exploratory personality traits. But between six and eight months of age, the time when cows reach sexual maturity, their reactions to novel scenarios were less stable.

“[T]here appeared to be a change in personality,” von Keyserlingk says. “This means that dairy cattle show consistent personality as calves and adults, but with a period of inconsistency around puberty.”

The forces driving these personality fluctuations are likely the same bodily changes that make human teenagers a handful for their parents. “Major physiological changes occur during sexual maturation, which may explain the inconsistency in individual behaviours and personality traits from the juvenile period to the adult period in our study,” the researchers note. “Steroid hormones around puberty give rise to reproduction-related behaviours typically involving increased risk-taking, exploratory and agonistic behaviours.”

Why does it matter that cows experience emotional turbulence during their adolescent years? For one, understanding the individual needs of cattle could help farmers better manage livestock and optimize production; studies have shown that stressed out cows produce less milk. But to animal advocates, studies like these help narrow the gaps between humans and farm animals, highlighting the need for more compassionate farming methods.

“[I]n the end,” Lori Marino, a neuroscientist and executive director of the Kimmela Center for Animal Advocacy, tells Ian Sample of the Guardian, “it tells us that if cows and humans share so much of their psychology with each other, we need to look at cows as beings who also have feelings about being farmed and having their children taken away from them in the dairy industry.”

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