Immediately after birth on many dairy farms, baby cows are separated from their mothers and housed in their own pens to protect them from getting sick. Two months later, they join the herd.

But early-life isolation may be depriving baby cows of the opportunity to reach their full potential, found a new study. Compared to calves raised in pairs, isolated calves were much slower to learn new things and had a harder time adapting to changes in their environment.

Aside from animal welfare concerns, the new findings suggest that dairy farmers have long been overlooking the brain development of their cows by depriving them of social interaction in their early weeks.

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“Imagine I said that instead of sending your child to kindergarten, I could put him in the classroom one-on-one with the teacher and all the same resources,” said Daniel Weary, a professor of animal welfare and dairy science at the University of British Columbia in Vancouver.

“But at the end of the day, if we found that individuals in this system were showing cognitive deficits in relation to other individuals, we would feel bad about that.”

For cows, he said, “it means we’re not keeping these animals in an environment that allows them to be what they can be and should be.”

Diseases spread quickly through cattle herds, and calves are particularly vulnerable, so for generations, traditional farmers have raised newborn cows in their own pens for the first six to eight weeks until they are weaned from milk.

On the research farm at the University of B.C., though, Weary and colleagues noticed that calves that had been raised alone had trouble adjusting to the group when they were finally moved over. They couldn’t navigate the big pen. They struggled to use the group feeder.

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It was like “the annoying kid in the school yard who always followed you around,” Weary said. “These individually raised cows don’t seem to know how to regulate their behavior around other animals at all.”

Suspecting that these problems might be rooted in the brain and not just an example of social awkwardness, Weary and colleagues separated 18 calves from their mothers within six hours of birth. They assigned eight of the young cows to solitary pens and 10 to be kept in pairs.

Starting at about a month old, calves were trained on a simple Y-shaped maze that allowed them to choose between a white bottle at the end of one branch and a black bottle at the end of the other. All of the young cows learned quickly that the white bottle was full of delicious milk while the black one was empty.

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Once the cows knew the drill, the researchers switched it up so that only the black bottle contained milk. After just a few trials, calves that had been raised with others figured out that they should now go for the full black bottle instead of the empty white one, the researchers report today in the journal PLOS ONE.

Calves raised alone, on the other hand, were still making many mistakes after eight or nine chances to learn that the reward had moved.

In another experiment, calves that had been raised with a pen-mate quickly got used to the introduction of a plastic red bin into the maze, while isolated calves never stopped sniffing, licking and pushing the strange object around.

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Without a companion to make their living environments more complex, the findings suggest that calves have a much harder time getting used to change.

Modern dairy farms tend to be complex places, Weary said, full of robotic milkers and computerized feeders. Housing calves in pairs -- instead of alone or in larger groups -- could be a simple way to make cows more adaptable to evolving methods without increasing the risk of illness.

The new study reinforces evidence that calves raised alone may be more likely to act abnormally and have trouble coping, said Catherine Douglas, a cattle behaviorist at Newcastle University in the United Kingdom.

Those kinds of stresses could potentially lead to other negative consequences for cows and farmers, she said, making the animals harder to manage. In her work, she has also found that stressed cows kick more and are slower to let down milk.

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Other recent studies have found that calves raised together are quicker to approach food and are more socially adaptable, added Marcia Endres, who studies animal behavior and welfare at the University of Minnesota, Twin Cities.

But adopting new farming practices is not as simple as reorganizing housing pens.

“It’s like having your kids go to daycare,” Endres said. “If they’re home, they’re not exposed to other kids and they don’t get sick. But when they go to daycare, they bring home all sorts of diseases."

"You have to be aware that when you put animals together when they’re young, they might get sick more,” she said. “It takes a little different kind of management. There are always different sides of the story.”