They don't moo just to annoy you. Unless you get annoyed easily and you are the one who is finding their bawling irksome (no offense of course...). There are several reasons why cattle will moo consistently:
"Moo cows" are, essentially, cows that moo.
yes all cows moo.
To the moo-vies! UK cows go to Uddersfield it likes to eat moo-slie at the moo-vies
Yes.
No.
moo moo cows that are weird
They have a stuttering problem
Yes but only if its loud moo
Yes.
No, not usually.
Frogs don't moo because they aren't cows!
With dairy cows, yes. Other times cows (including beef cows) will moo when they are calling to their calves, or when it's feeding time, or even when they're in heat.