Sec. 15.03.06.06. Calibration of Equipment

A. Initial Calibration. Any person seeking to use automated testing equipment for measuring milk fat content in raw, unhomogenized milk as a basis of payment to producers shall first cause the equipment to be calibrated in accordance with these regulations. The Department shall be notified at least 10 State working days before initial calibration is to be conducted. The initial calibration may be performed only after the equipment has been installed and stabilized as approved by the Secretary. The initial calibration shall be performed by the equipment operator under the supervision of the Secretary, in accordance with the procedures approved by the Secretary. Subsequent calibrations shall be performed by the equipment operator in accordance with procedures approved by the Secretary, but need not be under the supervision of the Secretary.

B. Method of Calibration.

(1) The equipment operator shall obtain 20 representative samples of natural herd milk which have not been adjusted with skim milk, cream, or any other substance. Each sample shall be a representative mixture of the milk from any herd containing at least 20 cows milking.

(2) The collection and handling of the 20 representative samples shall be uniform and in accordance with milk sample handling procedures as set forth in the regulations of the Department.

(3) The milk fat content of the samples to be used as the natural herd milk samples shall be distributed within the ranges of 3 percent to 6 percent of milk fat and, if possible, reflect the expected milk fat content of the milk to be tested by the equipment.

(4) The samples shall be first tested for milk fat content using the reference method. Each sample shall be tested in triplicate. These samples shall then immediately be tested using the automated testing equipment and shall be tested in triplicate, using the automated testing equipment. All testing of the samples for purposes of calibration shall be completed within 24 hours from the time the samples were collected from the producer.

(5) The milk fat content for each sample as measured by the reference method shall be determined by taking the average of the three tests by that method. The three tests conducted using the automated testing equipment shall be averaged for each sample to determine its milk fat content as measured by that method. All averages shall be computed to the nearest 0.01 percent.

(6) Any sample, in which the fat content as measured by either method varies more than 0.10 percent during the course of being tested three times, may not be used in calculating the standard deviation of difference (Sd).

(7) The standard deviation of difference (Sd) shall be computed by using the averages of at least 18 of the 20 samples tested and applying the (Sd) formula used by the AOAC.

(8) The maximum allowable average difference (D) and the standard deviation of difference (Sd) between the results obtained by using the reference method and the results obtained by using the automated testing equipment may not exceed those established by the AOAC for the make and model of automated testing equipment used. Only automated testing equipment meeting these standards may be used to measure the milk fat in milk as a basis of determining the payment to producers.