"Livestock fatten faster when tasked on a Pen. Trains Sheep."
—In-game description
The Livestock Pen is an economic building in Age of Empires III. It trains livestock which can be tasked to the Livestock Pen to make them fatten at a faster rate.
Some civilizations do not have access to the Livestock Pen, but have replacement buildings instead. Native American civilizations have Farm instead of Livestock Pen which combines the functions of a Mill and a Livestock Pen, while the Chinese have Village instead of Livestock Pen which combines the functions of a House and a Livestock Pen.
Two civilizations do not have any access to the fattening capability because their Villagers cannot gather food from Herdables. The Indians have the Sacred Field instead of Livestock Pen that increases the experience generation rate of their livestock; the Japanese may use Shrines to generate resources over time.
Livestock Pens effectively cut the fattening time of most livestock down from 30 minutes to around 5-6 minutes. However, they are less common than gathering food directly at the Mill, especially in Supremacy. This is due to the more complicated mechanics of gathering from herdables, such as the upfront cost of invested food that cannot be used to train units.
If there is a 5-6 minute period for livestock to be fattened at the pen, such as during a Treaty match where military units are not required, livestock can be used as a worthwhile investment to multiply one's food. It is easy to adjust the amount of food and settler time invested by training more livestock units. The Fulling Mills card indirectly relates to this building by making it 4x faster to gather from herdables, saving villager time, reducing waste to spoilage, and freeing them to do other tasks.
"Keeping animals was important to the founding of the New World, especially as areas became settled and hunting became less abundant. Animals were used for food, but they had other uses as well. Fat from animals was used to make soap, the skins were used for clothing, and tallow was used in candles. Tallow was also used to keep leather supple and water-resistant."
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Sheep
Cow
Llama
Selective Breeding
Flying Buttress (+20%)
Gas Lighting (+4)
Cree Textile Craftsmanship (-25% wood)
Tupi Forest Burning (-20% wood)
Code Napoleon (+50% cost, French only)
Customized Merc Weapons (+30% cost, John Black's Mercenaries only)
Improved Buildings
Ranching
Llama Ranching
Land Grab
TEAM Improved Buildings
Age of Empires III
British
Dutch
Ottomans
Russians
The WarChiefs
Aztecs
Iroquois
Sioux
The Asian Dynasties
Chinese
Indians
Japanese