A pen for one breeding pair
Our starting plan is internal 5×5 blocks, a perimeter fence and an entrance through two gates with a gap of 2 blocks. These sizes provide space for grooming, but are not a requirement for reproduction. Remove steps of the ground near the external fence: animals can cross the fence through them. Reference: Minecraft: cows.
First build an entrance, then lead two adult cows with wheat. Walk in short sections, wait for a lagging cow; inside, remove the food from your hand and close both gates.
What to give to different species
Use food for two adults of the same species. Cows and sheep need wheat, chickens need seeds, pigs need carrots, potatoes or beets. Don't waste food on babies if you want a new pair of parents.
In cows, after the birth of a calf, re-breeding is available in approximately 5 minutes; without acceleration, the calf grows for about 20 minutes of active time of the site. Keep two adults separate from animals for meat.
Planting layout and harvest maturity are discussed in detail here: Your first wheat farm: water, farmland and harvesting.
Products without slaughter
A cow can be milked with a bucket many times. Milk also removes the beneficial effects of potions, so drink it mindfully. A sheep is sheared with shears; to restore the fur you need access to grass. Chickens lay eggs without a rooster and without feeding.
Don't keep your entire farm in one cell: it's hard to choose an adult and easy to hit the backup pair. A separate corral of producers is more convenient than a huge crowd.
The food yield and supply of planting material are calculated in the manual: A reliable food supply: crops, animals and travel rations.
