One of the main reasons we drink milk is for the calcium: the mineral makes your bones stronger, muscles healthier (including in your heart), and helps blood to clot.
Now, researchers at the University of Wisconsin-Madison have discovered a way to boost calcium levels in milk by giving cows regular injections of the hormone serotonin, a chemical messenger that, among other things, is linked to feelings of happiness.
If you think the life of a modern milk cow is already pretty happy—lounging in green fields under clear blue skies—think again. According to Modern Farmer:
With the rise of factory farming, milk is now a most unnatural operation. The modern dairy farm can have hundreds, even thousands of cows. Today’s average dairy cow produces six to seven times as much milk as she did a century ago. Cows spend their lives being constantly impregnated in order to produce milk… and, after roughly three or four years, their production slackens and they are sold off for hamburger meat.
Whether cows are “happy” or not isn’t necessarily a priority, though it has been shown that treating cows badly can lower milk yields. The modern cow has other problems, too—around 5-10% of US dairy cows suffer from low calcium levels, known as hypocalcaemia, causing problems with their digestion, ability to fight disease, and prospects for reproduction, all of which causes them to produce less milk.
Laura Hernandez, professor of lactation biology, and her team studied 24 cows—half Jersey and half Holstein, which are among the most common breeds. After the serotonin treatment, Jersey cows, who are more vulnerable to hypocalcemia, had noticeably higher calcium levels in their milk. But both breeds benefitted from the treatment, with raised calcium levels in the blood—important to the cow’s general health, while also signaling to the body to start reabsorbing calcium into bones. The researchers presented their findings in the Journal of Endocrinology.
Farmers and scientists have tried other methods to improve the moods of cows, including playing them relaxing music and reading them Shakespeare. Both reported increased milk yields, most likely due to eliminating stress, which is known to affect milk production.
Although it made their milk more nutritious, the serotonin treatment didn’t significantly affect the cows’ overall milk yield or how much they ate. But this was a study of a relatively small group of cows—Hernandez will have to show similar results in much larger numbers if the “happy hormone” therapy is to be rolled out more widely.