Bovo is gender unspecific. When we say "cow" we often think of the bovine species, but are using the feminine specific designation. There are perfectly reasonable historic reasons for this.
Virbovo = bull
bovo = bovine
bovino = cow
bovido = calf
gebovoj = unspecified number of bovines of mixed genders, cattle
bovaro = herd of bovines, or cattle
But a cowboy is vakero.
Then there is the silly thing I heard once; bobovoj = Cattle-in-law. Two ranchers got married …
One can really do some amusing things with the affixes in Esperanto. Fibovo? Bovema? Boveca? Bovero? Bovisto? Eksbovo? etc. For your edification & amusement you may now try to figure just what these different affixes have done to those poor cattle.