Moo?

Ok, a grown female is a mare. A grown male is a stallion, or if castrated, a gelding. Young females are fillies and young males are colts.

What is the common name of the animal? A horse (of course, of course)

Try this one:

A grown female is a cow. A grown male is a bull, or if castrated a steer. Breeds include Angus and Hereford.

What is the common name of this animal?