its more likely the artist was illustrating the mounting behaviour between bulling heifers. that's what i explained to you when i first replied; 2 heifers will definitely do that at some time in their life. if they begin bulling (getting randy, ready for serving) they will mount other heifers. there are also devices that can be glued onto their backs that indicate whether another cow has mounted her. thus telling you when she is ready.
one heifer actually tried to mount
me once, and i was only 16 at the time so i just grabbed hold of the gate. luckily, she hooked her hooves over the gate rather than my shoulders, otherwise i'd have been crushed. true story. never turn your back on a randy heifer. or a bull, which is worse.
and i want a 300 word essay on cattle calving procedures for next class, too.