Wisconsin Administrative Code
Department of Agriculture, Trade and Consumer Protection
ATCP 55-89 - Food, Lodging, and Recreation Safety
Chapter ATCP 65 - Milk And Milk Products
Subchapter V - Safety and Quality Standards
Section ATCP 65.78 - Milk quality test samples

(a) Whenever a dairy plant operator performs a milk quality test on a bulk milk shipment from a milk producer, the dairy plant operator shall perform that milk quality test on a test sample collected under s. ATCP 82.12.

(b) Whenever a dairy plant operator performs a milk quality test on shipment of milk in cans from a milk producer, the dairy plant operator shall perform that milk quality test on a test sample collected under sub. (3).

(c) Notwithstanding pars. (a) and (b), a dairy plant operator may use a composite sample, under sub. (4), to perform a Babcock test for milkfat or to perform another milk quality test approved by the division under sub. (4). A composite sample shall be compiled from fresh milk samples collected under par. (a) or (b).

(d) This subsection does not apply to a bulk load test for drug residues under s. ATCP 65.72(3).

(e) Upon reasonable notice from the division, a dairy plant operator shall provide the division with samples of producer milk collected under s. ATCP 65.38. The division may request samples once every 4 months, or more often as the department considers necessary for animal health and milk quality testing. Every sample shall be marked with the identification number of the individual producer from whom the sample was collected, and shall also indicate the date on which the sample was collected. A sample shall be kept at a temperature of 32º to 40º F. (0º F. to 4º C.) until it is transferred to the custody of the department.

(a) If a producer ships milk to a dairy plant in cans, rather than in bulk, the dairy plant operator shall collect a test sample from each milk shipment immediately after that milk shipment is transferred to the weigh tank at the dairy plant, and before it is commingled with any other milk shipment. The weigh tank shall be constructed so that milk poured into the weigh tank is completely mixed.

(b) If a weigh tank is not large enough to accommodate a producer's entire milk shipment, so that multiple weighings are needed, the dairy plant operator shall divide the shipment as evenly as possible between weighings and collect a sample from each weighing. The samples shall be of equal volume and shall be combined to form a single sample representing the entire shipment from the producer. The dairy plant operator may not split the contents of any single can of milk between weighings, but shall include all of the contents of that can in the same weighing.

(a) A dairy plant operator may use a composite sample to perform a Babcock test for milkfat, but may not perform any other milk quality test on a composite sample except with the division's written authorization. A composite sample shall be compiled according to this subsection.

(b) A composite sample shall include a representative sample of milk from each of 2 or more milk shipments represented by the composite sample. No composite sample may include milk from more than 16 milk shipments. Each component sample included in the composite sample shall have the same volume and shall include at least 10 ml. of milk. A composite sample shall include at least 150 ml. of milk.

(c) A composite sample container shall have a capacity of at least 240 ml. The composite sample container shall include an effective permanent closure that is attached to the container. The composite sample container shall be marked to identify the producer and the milk shipments represented in the composite sample.

(d) A composite sample representing a producer's bulk milk shipments shall be compiled from fresh milk samples collected from those shipments under s. ATCP 82.12. On the same day that a producer's bulk milk shipment is received by the dairy plant operator, or by 12:00 noon of the following day, the dairy plant operator shall transfer, to the composite sample, at least 10 ml. of milk from the sample collected from that milk shipment under s. ATCP 82.12.

(e) A composite sample representing a producer's shipments of milk in cans shall be compiled from milk samples collected from those shipments according to sub. (3).

(f) A dairy plant operator shall preserve a composite sample by adding potassium dichromate, or another preservative approved by the division, to the composite sample. Not less than 100 mg., nor more than 190 mg. of potassium dichromate may be used in each composite sample to obtain a concentration of 20 mg. per 30 ml. of milk in the completed sample.