What is a common sign of pain in cattle?

Teeth grinding, also known as bruxism, is a common sign of pain in cattle. This behavior can indicate discomfort or distress, as animals often grind their teeth to cope with pain. In cattle, teeth grinding might suggest issues such as gastrointestinal discomfort, dental problems, or other painful conditions.

The other signs, such as flinching and vocalization, can also indicate pain but may not be as specific in cattle as bruxism. Increased appetite typically does not correlate with pain; in fact, animals in pain often show a decreased appetite instead. Therefore, teeth grinding is a more definitive indicator of pain in cattle, making it the correct choice.