Which species of livestock does not exhibit heat?

The correct answer highlights that sheep, unlike the other listed species, do not exhibit an estrous cycle in the same visible way that pigs, cattle, and goats do.

Sheep have a more subtle reproductive cycle compared to these species, which display clear signs of heat or estrus. Pigs show prominent behavioral changes during estrus, such as increased vocalizations and restlessness, while cattle and goats exhibit noticeable signs as well, like mounting behavior and changes in appetite.

In contrast, sheep may not exhibit overt behavioral signs, making it less apparent when they are in estrus. Their receptivity to breeding may instead be inferred from physiological changes rather than observable behavior, which can lead to the misconception that they do not exhibit heat. Understanding these differences is crucial for effective breeding management and livestock production.