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diagnostic testing for dairy herds

A1/A2 (beta-casein)

The A2 genotyping assay identifies the A1 and A2 beta-casein status of individual animals, providing insight for strategic breeding to develop A2 herd status. The A2 isoform of beta-casein is potentially better digested than the A1 isoform. Milk containing only the A2 isoform (A2/A2) is currently being marketed as an alternative to traditional fluid milk.

Sample Type(s)

  • Whole Blood 
  • Tissue (fresh or frozen)
  • Milk (fresh, frozen, or preserved)


  • Test at any age or time at your convenience


  • Available within 10 days of sample receipt
  • Reported as A1/A1, A1/A2, A2/A2, or retest


  • Blood and tissue: 99% accurate
  • Milk: 94% accurate; ‘Retests’ should be verified by blood or tissue


  • $13.75/sample
  • Testing billed upon sample receipt
  • $10 sample submission fee per order

Submit Samples

CentralStar Laboratories

CentralStar’s Laboratories provide sample analyses on milk, blood, fecal, and tissue samples for a variety of production, disease and health-related traits.

More than 5.3 million samples are processed annually using state-of-the-art equipment and techniques including infrared spectroscopy, flow cytometry, ELISA, PCR, and more.

Testing Supplies

For convenience, shippers and sampling supplies can be purchased online.

Diagnostic tests are intended to identify diseases in the cow for their health, and do not determine the “safety” of milk. Testing prices listed effective 10/1/2020. 

How To Collect a Blood Sample for Cattle Pregnancy Testing

Supplies Needed:

  • Vacutainer® Vial
  • Double-sided needle
  • Needle holder

Be sure to check which type of vial is required for your desired test type.

  • Red-top vials: Pregnancy, Johne’s, Leukosis, BVD and Neospora.
  • Purple-top vials: A1/A2 and BLV SSI PCR.
test step 1

Step 1:

Screw needle into needle holder
Insert the Vacutainer vial into the holder
DO NOT puncture the vial stopper

test step 2

Step 2:

Lift the tail straight up and clean area
Find the midline groove 4 to 6 inches from the base of the tail
Insert the needle about ¼ inch into the groove, perpendicular to the underside of the tail

test step 3-4

Step 3:

Engage the vacuum by pressing the vial up puncturing the stopper
If blood does not flow, carefully redirect the needle
DO NOT remove the needle from the tail

Step 4:

Once blood begins to flow maintain needle position
Collect a minimum of 4cc of blood

test step 5

Step 5:

Disengage the vial from the holder BEFORE removing needle from the tail


test step 6

Step 6:

Clearly label vials with animal identification
Fill out a sample submission form

Step 7:

Keep vials at room temperature to allow clotting (1 to 2 hours)
Once clotted, keep samples refrigerated until submitted to the lab


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