Breed Animals in Minecraft

Since Minecraft 1.3.1, breeding animals has been hard. This article will help.

Steps

Build a fence. The bigger you make it, the more space your animals have to move around. You will also have more space to get in or out without the animals instantly getting out.
Get seeds for chickens; wheat for cows, mooshrooms, and sheep; golden apple/golden carrot for horses and mules; raw fish for cats; carrots for pigs; any kind of meat (except fish) for wolves. Wolves can also eat rotten flesh from zombies.
Put your fence down in squares.
Lure each animal into the fenced area by holding their respective bait.
Give two animals of the same species their bait, and they will enter love mode.
You will notice that a baby has popped out.

Collect eggs from wild chickens. The more you collect, the better but at least 32 are needed.
Create an enclosure wherever you want to place the chicken farm.
Throw eggs into the enclosure. To do this, right-click with eggs selected. About one in every 4 eggs thrown will spawn a baby chicken. 1 in every 32 eggs thrown can hatch 4 chicks.
Baby chickens will grow up to be adult chickens, which lay eggs. Collect the eggs.
Please repeat steps 1-4 until satisfied!

If the pregnant mother is next to the fence, the baby can be generated on the other side of the fence.
Make sure you have more than 3 wheat with you or the animals will probably not follow you.
Another easy way, other than an airlock, is by using nether fence in a gap between the normal, wooden fence. Mobs cannot go in and out, however you can.
If you want to use a bow and arrows you will want to raise chickens for the feathers you need to craft arrows.
Keep a good stock of wood, you never know when you will need it.
The current mobs that can spawn are: cats, dogs, pigs, sheep, chicken, cows, horses and mooshrooms.
The mobs that can breed are: pigs, sheep, chickens, wolves, cows, horses and mooshrooms.
Make sure you have at least three specimens of the same animal before killing some. Otherwise you'll have to re-capture them.
- Chickens breed with seeds.
- Cows mooshrooms and sheep breed with wheat
- Horses breed with golden apples
- Dogs breed with porkchops
- Pigs breed with carrots
Rabbits will breed rapidly if more than one is in the area.
Make sure you have a large area for rabbits.

Your farm can get out of hand at a fast rate if you're not careful. Be sure to breed in a large, open space!
Your animals might escape when you enter/exit the pen. You can get around this by making an "airlock" with two doors. Open the first door, go through, close it, and then open the second so that no animals escape.