Cattle only beller when they are distressed, especially if they were separated from the herd, or a calf is separated from his momma (most often vice versa).
Heifers and cows also moo when they are in heat, and bulls roar, growl and rumble when they are trying to impress their female harem or challenging another bull that is competing with him for breeding rights.
Cows and heifers may groan as they give birth, but some cows don't make any sound at all, especially if it's an easy calving for them.
Lastly, cattle also beller when they hear the tractor or truck start up or see someone walking in the corral because it often means it's feeding time, and they're alerting others to get up and head for the feeding station.
So cattle moo to alert others, when they are in distress (pain, panic, loneliness), to challenge another bovine or even a human or dog, and even when they are protesting to something they don't want.
And the why they moo is because it's the only form of verbal communication they are capable of because of their inflexible lips, thick, long tongue and their vocal cords are a bit different than humans.
· 9 years ago