Dairy cows face a lot of pressure. Every day, month after month, a lactating cow is expected to let down her milk under the expectant eyes of a farmer whose bottom line depends on how much it he can squeeze out.

Now, new research suggests a gentle way to get more milk out of anxious mama-cow: Stroke her, ask about her day, and call her Elsa, Rose, or Lady Moo. Cows with names produce up to five percent more milk, according to a study published in January in the journal Anthrozoos.

It's not the name itself that makes a dairy cow more productive, said cattle behaviorist Catherine Douglas, of Newcastle University in the United Kingdom. Rather, a cow with a name is likely to be more relaxed than if she were treated as just another number.

Previous studies have shown that elevated stress hormones like cortisol reduce milk production by interfering with the milk-boosting hormone oxytocin, among other effects. Anxious cows are also more likely to stomp and kick, making milking more difficult.

"If you call a cow by name, it indicates that perhaps you talk to her more, perhaps you consider her more of an individual, perhaps you have more of a one-to-one relationship," said Douglas, who has seen firsthand the consequences of stress in a cow. "Personally, I have had a black eye and broken ribs from milking."

For the current study, Douglas and colleague Peter Rowlinson wanted to investigate how a cow's relationship with people affects her behavior and productivity. Through questionnaires, the researchers surveyed more than 500 farmers across the U.K. about what they thought of their cows and how they treated the animals.

On nearly half the farms, results showed, cows were given names. And compared to their nameless peers, heifers with individual identities produced an average of 258 more liters of milk over the 10-month milking season, or about an extra liter a day. An average cow produces about 7,500 liters of milk each year.

Dairy cows don't start making milk until they're two years old, so farmers often ignore them from the time they're born until they start producing. But the new study also found that when young heifers received extra attention between the ages of six months and 15 months, they produced more milk later on.

The new results echo similar studies of other animals, said Ian Duncan, the Chair in Animal Welfare at the University of Guelph in Ontario. Anxious chickens lay fewer eggs, for example. Fearful pigs and sheep grow more slowly. Even trout quickly learn to swim away from scary situations, and fear causes them to eat less.

"It seems natural to me that you would get these sorts of findings," he said. "It just adds to what we already know."

As farming practices become more automated, Duncan added, it might become even more important for farmers to take time to visit with their animals. He also hopes the work will lead to a shift in how consumers shop.

"I think in the future we will see food items, including eggs, milk, and meat, with labels that guarantee these animals had a certain quality of life," he told Discovery News. "It's something we're working on."