Section 29A. Said chief of the bureau of milk marketing shall, after reasonable notice to all interested parties and a hearing, prescribe, and may from time to time in like manner modify or amend, rules and regulations to govern the methods and frequency of making tests for determining the milk-fat or other component content of milk or cream for purposes of inspection or as a basis for payment in buying or selling and to govern the procedures for determining the proper basis for payment by the measuring, sampling and accepting of raw milk at dairy farms for inclusion in bulk tank trucks.