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  Home > Submission Guidelines > Submission for Udder Health Testing > Collecting Samples

Collecting Samples

General Information

Collect high quality samples for accurate diagnosis. Laboratory results are only as good as the techniques used in collecting and transporting the samples.

Plastic test tubes with snap-on lids work well if the lids are completely closed and the tube is filled about one-half full. Do not fill tubes more that 1/2-3/4 full.

Whirl pack bags should not be used because they frequently leak during shipment. Whirl packs also frequently become contaminated while taking the sample.

Styrofoam boxes are available from the Laboratory for Udder Health. These boxes are specially designed and intended for milk sample shipment only. They contain cold packs and tubes for sampling bulk tanks or individual cows.

Collecting from Individual Cows

Individual samples should be taken from affected quarters of cows with clinical mastitis. Composite samples are suitable for cows with sub-clinical mastitis or for screening for contagious pathogens. When composite samples are taken, nearly equal amounts of milk should be taken from each quarter.

Please follow these steps carefully to avoid contamination:

  • The hands of the person collecting the sample must be clean and dry. Wearing latex or vinyl gloves is preferable.
  • The person collecting samples should not be milking at the same time.
  • Samples should be taken directly from teats. Bucket or milk meter samples carry over bacteria from previous cows.
  • It is best to sample at milking time (before milking the cow). If the sample is taken during midday, it should be taken at least 4 hours after the last milking.
  • Sample tubes should be handled properly to ensure sterility at all times. The collection tube should be held at an angle (approximately 45 degrees). Do not put caps into pockets, touch the tops or touch the inside of the collection tubes. Avoid getting particles of dust, dirt, or manure into/on the sample tube. If possible, label the collection tube with the proper cow identification number prior to sample collection. Use a waterproof permanent marker to label.
  • The most important factor is that teats need to be clean and dry. Prep the cow as usual, but teats need to be dried completely by the person doing the sampling.
  • After the routine teat preparation, scrub the teat ends thoroughly with alcohol swab or sterile cotton ball saturated with alcohol. Clean the teats on the far side of the udder first. Be careful not to touch teat ends before taking the milk sample. Sample the teats closest to you first. Discard a squirt or two of milk before sample collection.
  • While holding the tube at an angle, collect a squirt or two of milk from each quarter being sampled. If collecting milk from all quarters (composite sample), try to take the same amount of milk from each quarter. BE CAREFUL NOT TO TOUCH THE TEAT END DURING SAMPLE COLLECTION.
  • Open barn doors or tunnel ventilation can cause massive air movement, resulting in major contamination problems from bedding and dust. Feeding during sampling should be avoided.
  • Tighten the cap and properly label the collection tube using a water proof marker. Immediately place in a refrigerator or freezer. Keep cold or frozen until delivery to the Minnesota Veterinary Diagnostic Laboratory. Bacteria in samples that are not cooled or frozen may grow, resulting in misleading information.

Collecting from Bulk Tanks

Please follow these steps carefully to avoid contamination:

  • Collect samples 3-5 days in a row. Five day sampling procedures achieve more accuracy than single day sampling for contagious pathogens such as Staph aureus. Agitate the tank well before sampling.
  • Use a clean dipper or sterile syringe to draw the sample from the top of the tank. If using a syringe, collect approximately 5-10cc. Empty the syringe immediately into a clean milk collection vial. Fill the tube one-half full (Remember, milk expands when frozen).
  • Please do not send milk samples in a syringe as the plunger frequently comes out during transit and introduces contamination.
  • Place immediately in the coldest part of the freezer. Do not delay! Extensive delays will allow bacteria to grow giving erroneous results

IMPORTANT: Do not collect samples from the outlet valve unless absolutely necessary because samples collected in this manner often will be contaminated. If you must collect from the outlet valve, allow 1-2 gallons of milk to run before collecting the sample (you can catch the excess milk cleanly and return it to the tank).

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