Answer: Music

In 2001, a pair of researchers at the University of Leicester in England made light-hearted headlines with their study indicating that cows exposed to music produced 3% more milk (not an insignificant increase for dairy farmers’ production quotas).

Not just any music, mind you; the cows have a strong preference for slow-tempo music like R.E.M.’s Everybody Hurts, Orinoco Flow by Celtic Woman, and What a Difference a Day Makes by Aretha Franklin. Cows exposed to faster-tempo music like dance hits and club mixes showed no increase in milk production.

The researchers didn’t have to tell dairy farmers twice, however, as farmers in both Europe and the United States had long been playing music to their cows. A dairy barn running at full operational speed is a noisy place and farmers had been playing soothing music like classical, slow country songs, and soul music to their cows for years.

Adding a twist and a bit of fun to the whole affair, the British Columbia Dairy Association, in 2012, called on the public to create play-lists for the cows in Canada. The cows “voted” with their milk production and the Association released lists of cow-friendly songs as part of their Music Makes More Milk contest.