The eyes were painted on the cattle's butts.
Went looking for images, the article did not disappoint: https://www.nature.com/articles/s42003-020-01156-0/figures/1
Went looking for images, the article did not disappoint: https://www.nature.com/articles/s42003-020-01156-0/figures/1
Went in expecting a couple of crude round spots for eyes
Got ACTUAL EYES with the whites, iris\pupil, darkened rims, even a suggestion of tear ducts