Leviticus 22:21, 23

When someone offers a sacrifice of peace offerings to the LORD to fulfill a special vow or for a voluntary offering, of the herd or of the flock, it must be without defect to be accepted; there shall be no defect in it.

Now as for an ox or a lamb which has an overgrown or stunted member, you may present it as a voluntary offering, but for a vow it will not be accepted.