The calf's temperature is 40.5. Is it normal to wag its tail on its stomach?

Not normal. The calf's body temperature is 40.5℃, which is a mild fever symptom. The calf's temperature should be between 38.5℃ and 39.5℃. If the body temperature exceeds 39.5℃, it is in a fever state. Wagging its tail is an untimely performance of the calf, and it may also be an emotional reaction. Calves may have different symptoms such as loss of appetite, poor spirit and elevated body temperature during fever. It can also lead to a series of health problems, such as dehydration and indigestion.