The Sacred Field is a building unique to the Indians in Age of Empires III: The Asian Dynasties. It trains Sacred Cows for 125 food (100 food if the "Goraksha" card is sent). Livestock tasked to the sacred field generate experience instead of fattening.
Sacred Fields can heal nearby units if The Mystical Syllable card is sent.
"As a source of food and a symbol of life in Hinduism, the cow may not be killed. According to the ancient religious text, the “Rigveda,” the cow is a goddess associated with Aditi, the mother of all gods. Therefore, slaughter is taboo. In ancient times, cows were sacrificed and their meat eaten, but never primarily for consumption, and milk-producing cows were never killed. Even during periods when meat-eating was permitted, vegetarianism was encouraged.
On a more practical level, slaughtering cows for beef was an extremely expensive act for sacrifice or as a gift, since the animal was a source of many important products: milk for consumption, fuel from dung, and browned butter for lamps. Later, in the early centuries CE, the cow became an appropriate gift to priests of the higher caste, or Brahmans. It was even said that killing a cow was equal to killing a Brahman."