Hybrid pigs

Hybrid pigs are domesticated half-pig animals encountered by Zuko during his brief stay at an Earth Kingdom farm. They generally resemble pigs, but have the horns and coloration of other animals.

Known types
There are various types of hybrid pigs raised on Earth Kingdom farms and in the Fire Nation military.

Wooly-pig
A wooly-pig is a hybrid of a sheep and a pig. This animal is bred to make use of its wool, which can be used to create various clothing pieces. The wool gets particularly muddy, however, because the wooly-pig tends to roll around in the muck. The meat of the wooly-pig can also be used for food.

Moo-sow
A moo-sow is cross between a cow and a pig. It produces a special and delicious pig-milk favored by the people of rural towns. The hybrid also provides rich meat that can be used for food. Kept in pens by the Fire Nation military, they were also used for physical training.

Picken
A picken is a cross between a pig and a chicken. This creature lays eggs that can be sold in dozens. It can also be cooked in various manners, and made into a variety of dishes.

Pigster
A pigster is a cross between a pig and a rooster that make great alarm clocks.

Pig-deer
There is very little information known about the pig-deer, apart from its physical structure. A pig-deer exhibits the facial structure of the pig and generally has the same body shape. However, each pig-deer has two antlers protruding from its head, and fur covering its entire body. They are a mix of a pig and a deer.

Trivia

 * Co-creator Bryan Konietzko noted that hybrid pigs took the concept of hybrid animals to a ridiculous extreme.