The Animania mod adds about 4-6 breeds of cows, sheep, chickens and pigs to the world.  
You can feed them using a trough, and try your best to keep them happy.  Each produces
slightly different meats or eggs or hides -- they are seriously cute and fun to have
around.  Just don't ket them get too bored.

The pigs want some mud to play in, and you can right-click seeds onto the ground for the
chickens to eat.

The mod also adds frogs and ferrets and hamsters to the world.  Even a hamster ball.
Even a hamster wheel that generates energy.
 