Bones

Bones is a mod that adds a bunch of rare skeletal mobs to the nether. There are four new mobs, the Skeleton Sheep, Pig, Cow and Chicken.

Each animal can be bred with the meat of their flesh-bearing counterpart.
Skeleton sheep can be fed rotten flesh for a chance to regrow its skin, which can be harvested for mutton.
Skeleton pigs can be ridden just like regular pigs, but are faster and require a porkchop on a stick instead of a carrot on a stick.
Instead of eggs, skeleton chickens lay items such as charcoal, fire charges and gunpowder.