John Calvin on Leviticus 22:22-24

22. Either a bullock, or a lamb, that hath anything superfluous. An exception is here stated as to free-will-offerings; for in them God does not refuse a diminutive animal, or one which has a member either contracted, or of excessive size. And doubtless a greater license ought to be given, when a person is not under the obligation either of a vow or any other necessity. Still we must remember that no victim is acceptable to God, which labors under any notable defect.