Aren't cows the females and bulls the males?
Or do I have that wrong?
Either way

Unless something has changed since I was a kid then
From what I remember and I admit that it was a long time ago. The girls are cows. The boys are bulls.
A young cow is a heifer. A bull that has had it's nuts ripped off is a steer.
The animal trying to hump that dude is almost certainly a young bull, because I don't think that cows roll like that; unless that is some new age diesel shyt.