Licensed dairy technicians shall personally take all samples, conduct all tests, and determine all weights and grades of milk and milk products bought, sold, or delivered upon the basis of weight or grade or on the basis of the milk fat, nonfat milk solids, or other components contained therein. Each licensee shall keep a copy of every original report of each test, weight, or grade made by him or her for a period of two months after making the report. No unfair, fraudulent, or manipulated sample shall be taken or delivered for analysis.