Antonyms for the phrase "are bred" might include concepts such as "are not produced," "are not cultivated," "are not developed," or "are not propagated." These antonyms suggest a lack of intentional breeding or cultivation, or perhaps the failure of a breeding or cultivation attempt. Other antonyms could include "are wild," "are mixed," "are natural," or "are untamed," suggesting a lack of human intervention or a more free-form genetic makeup. Depending on the context in which "are bred" is used, there could be a variety of antonyms that apply to convey a lack of intentional or controlled breeding or cultivating.