Which of the following is a common sign of heat in dairy cattle?

Restlessness is a well-known sign of heat in dairy cattle, often described as an increase in activity or nervous behavior. During this period, cows may exhibit behaviors such as pacing, mounting other cows, or vocalizing more frequently as they seek to mate. This heightened activity level is a result of hormonal changes that occur when a cow is in estrus, making them more likely to seek out a breeding opportunity.

In contrast, increased milk production typically does not correlate with a cow being in heat. While hormonal changes can affect milk production, these changes are more relevant to lactation stages rather than estrus. Similarly, frequent urination can occur in some cattle but is not a definitive sign of heat and can happen for various reasons including hydration levels or other health issues. Decreased appetite is also not commonly associated with being in heat; in fact, many cows maintain or even increase their feed intake during this time as the energy requirement for heat can lead to greater food consumption. Therefore, restlessness stands out as the clear indicator of a cow in estrus, making it the correct answer for identifying signs of heat in dairy cattle.