This is the same bull. It is attempting to mate
with this cow which is loudly protesting. Having
failed to capture his own harem his only hope of
reproducing is to sneak his genes into another
bull's harem when the dominant bull is not watching.
This cow is part of a larger bull's harem.
The calf in the foreground is only a few hours old. It
was trying to nurse when this bull interrupted it.
Moments later the attempt was interrupted by the
alpha male that owns this harem.
see the following photo