What do animals do when humans are not watching? Apparently the animals are actually rather "happening" folks when left to their own devices, as Barnyard tries to show in its party sequences (that go on for wayyyy too long). And yes, all the male "cows" in this movie have udders, which is surely going to confuse anyone who has the most rudimentary knowledge in animal biology.
Otis (Kevin James) is a bull that refuses to settle down into a more responsible role on the barnyard as set by his father Ben (Sam Elliot), which is to protect the animals against the threat of coyote attacks. However, following a run-in with the coyotes, Ben is unable to assume his position as barnyard protector, and Otis must try to step up to the role. And that is basically the entire premise of the movie, except that it takes a lot of gags and pointless side stories to get there.
Aside from the humour, Barnyard is simply a boring movie — the moral of the movie has been done to death, and the animation is weird, alternating between unreal (the cows) and very realistic (the coyotes). Too many ideas are raised and then dropped just as quickly, and the whole film just feels very haphazardly slapped together.