How to Take Samples—Milk


Milk

Sample size required: 50 cc’s or 1/3 cup

Vials with preservative are available from the lab. Milk with preservative will be stable for 7 to 10 days at 40 degrees to 70 degrees. Non preserved milk should be refrigerated immediately and transported to the lab within 24 hours.

Metered Milk

Mix metered milk according to manufacturers specification. Pour mixed milk in to clean leak proof container. Transport to lab promptly.

Bulk Tank

Agitate tank for 5 to 10 minutes. For a single sample dip out agitated sample into clean leak proof container. For duplicate sampling, dip out into a separate container enough milk for all samples to be run. Mix sub sampled milk and pour into clean leak proof container. Transport to lab promptly.

Individual Cow

Milk cow off line in fresh cow bucket. Mix milk in sealed bucket. Pour mixed milk into clean leak proof container. Transport to lab promptly. It is important to note that hand striping the milk from the cow will not produce an accurate test result. First milk is generally higher in protein while later milk is generally higher in fat. Somatic Cell Count also fluctuates during the milking process.

Milk Culture Sampling

The most important aspect to collecting a milk sample for culturing is making sure that the cow, the sampler, and the barn environment does not contaminate the sample. Following the directions below will greatly reduce the risk of contamination.

Containers
Sterile glass or plastic vials are suitable for collecting the milk. Do not open the container until you are ready to collect the sample. If using a container with a cap, do not allow the cap to touch any surface.

Collector Preparation
Wash and dry hands with a clean paper towel before sampling. If possible, have someone who is not milking take the sample to avoid contamination from other cows.

Udder Preparation
Try to sample each cow before milking, to avoid contamination from the milkers, liners, etc. Prep the udder as normal, and make sure the teats are clean and dry. Using a separate sterile swab or cotton ball for each teat, swab the teat ends with alcohol. Clean the teats that are farthest from you first, then those nearest.

Sample Collection
Sample the teats nearest to you first. Discard the first few squirts from each teat before collecting into the bottle, and avoid touching the bottle with the teat ends. Hold the cap of the bottle so the inner surface is neither touching anything nor facing up. Direct milk at a nearly horizontal angle into the bottle. Try to sample an equal amount of milk from each quarter if you are not testing each quarter separately. Cap the bottle immediately after collection.

Sample Storage
Cool or freeze samples immediately and keep cool until arrival at the lab. It is best to have the samples cultured within 24 hours of collection.

Bulk Tank Samples

Take samples four to five days in a row. Agitate the tank for 5 minutes before sampling. Take samples from the top of the tank with a sterile syringe. Samples may be transferred to a sterile vial if desired. Freeze sample immediately after collection. Pack samples in ice so they stay frozen during shipment to the lab.

Stearns DHIA Laboratories
825 12th Street South, PO Box 227
Sauk Centre, MN 56378-0227
320.352.2028 · 800.369.2697
Fax 320.352.6163 · Email

 

Hours
Monday-Friday: 8AM-4PM
Front Entrance Drop-Off Open 24 Hours
Refrigerator Available for Water, Milk,
and Wet Feed Samples