It is something I do not understand, my misconceptions about American's having Cowboy heritage are obviously wrong, unless it is a comic strip / animated cartoon thing!
Several films recently have also had Bulls with udders - trust me you do not want to milk a Bull (hopefully!)
The film Barnyard appeared to have 3 genders - Heffers (with udders), "Male Cows" (with udders) ??? and Bulls (without udders) - go figure?!?
Though in Scotts defense, horns are not an indication of gender and are specific to the type of cow (though size of horn can be).