[If] a calf’s tail does not reach the knee joint —- the Sages said: The growth of all calves is in this manner, as long as they grow they stretch out. Concerning which knee joint did they speak? Said R’ Chanina ben Antignos: Concerning the knee joint that is in the middle of the thigh. By reason of these blemishes a bechor may be slaughtered, and unfit consecrated animals may be redeemed because of them.