von Keyserlingk, M. A. G., Amorim Cestari, A., Franks, B. 2017. Dairy cows value access to pasture as highly as fresh feed. Scientific Reports 7, 44953.
Many dairy cows in the developed world are now housed exclusively indoors with fewer than 5% of the 10 million lactating cows in the United States having access to pasture during the grazing season. Indoor...