Bacteria and Regulatory Testing

Every time a milk truck takes milk off the farm, a bulk tank sample is pulled. Most bulk tank samples in the Northeast come to Dairy One for this analysis. Results are sent to the milk marketing cooperative and producers are then paid based on the fat, protein, and quality (somatic cell count) of these bulk tank samples. So, it is important that results be timely and accurate. In addition to the “producer payment” function of these bulk tank samples, they are tested for a variety of things from antibiotics, to added water.

If a farm is treating a cow for mastitis or some other infection and they suspect that cow’s milk did not get withheld from the tank, a sample is taken and sent to this lab for testing. The presence of any contaminants or added water can mean serious fines or in some cases, dumping entire loads of milk. The Bacteria Lab plays a critical role in assuring the milk from the farm can proceed to the milk plant and onto the retail supermarket shelves.

Submitting Samples

  • Ship in a cooler (s) with ice packs and temperature control “TC” sample. Stabilizing samples with small bubble wrap or paper is recommended as packages get jostled in transit and can arrive spilled if not supported or cushioned.
  • Ship overnight delivery to Dairy One Bacteria Laboratory.  See address below.
  • Samples must be labeled with legible sample IDs.
  • Samples must be sterile and without preservative. 
  • Sample volume is a sterile 2 oz vial filled to the etched line. 

Please include a completed copy of the Official Milk Lab Testing Form when submitting samples.

Milk Culturing Service

Milk Culturing is provided through a partnership with Dairy One and the Cornell University Quality Milk Production Services, and the Penn State Diagnostic Labs.  Samples are collected by your Dairy One DHI technician on test day.  They are frozen and travel to the culturing laboratory on Dairy One’s temperature-controlled trucks.

Results are sent back to the farm via mail, email, or fax and are available through the DHI technician’s computer.  Users of Dairy Comp 305 and Scout can download their culture results directly into their cowfile from the iLOOP.

Allow 4 business days for aerobic and 10 days for mycoplasma results.


  • Reference method for determination of Somatic Cells in raw milk or basic bacterial ID 
    • Sample is smeared onto slide and stain is added after which bacterial cells or somatic cells are counted 
      • Counting method used is Single Strip Factor

Farm Water Testing

  • Colilert
    • Presence/absence method
      • (MMO/MUG)
    • Substrate added to sample
      • Sample is considered positive for presence of Coliform after 24 hours if there is a color change
      • Sample is considered positive for presence of Coliform and E.coli if there is a color change and sample fluoresces under black light
  • Membrane Filtration
    • Sample is filtered through a vacuum and incubated for 21hours
      • Growth of colonies indicates presumptive p

Please include a complete copy of the Report of Bacteriological Water Examination when submitting samples.

Dairy One Bacteria Lab Shipping Address:

Dairy One Bacteria Lab
720 Warren Rd
Ithaca, NY 14850