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Laboratory pasteurized count reduction procedures

David R. Bray Published on 09 October 2010

The LPC test is doing a standard plate count on pasteurized milk. The mastitis pathogens are killed and what remains are organisms that keep on growing in the milk and reduce shelf life. These organisms are not from cows’ udders. They are usually spore–formers, like bacillus or pseudomonas, which live in rubber hoses and some water supplies. If a high LPC count is present (250 to 300 cfu/ml is the usual cut-off point), use the following procedures to ensure you stay below these levels.

1. Milk clean, dry, pre-dipped teats and udders.
Sand bedding and muddy lots are big suppliers of non-cow bacteria. Milking wet and/or dirty teats will load up the tank with them.

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2. Replace all rubber parts in the milking parlor: milk hoses, wash hoses, jetter cups, pipeline gaskets, milk pump gaskets and butterfly valves, etc.
While taken apart, inspect inside of the pipelines for build-up or milk stones, including the pipeline from the milk pump to the bulk tank. Replace all rubber parts every six months. No chasing of milk, especially not with a rubber hose.

3. Wash out pulsator lines.
They should have cleanouts on the corners so they can be flushed out. Remove the twin pulsator hoses from the claw and run hot soapy water through them and the pulsators. Most pulsators will take a quart of water. Rinse pulsators and change hoses if they are old. Dried milk film may be a big problem of high LPC’s.

4. Wash out vacuum supply lines, trap to pump, balance tanks, etc.
Do not run water into vacuum pumps.

5. Inspect the inside of bulk tanks.
You need a black light or big flashlight and a skinny person. Let the tank air out. If any internal cleaning of the tanks is needed, use a non-scratch 3-M scrubber, soap and water. Do not use acids or strong chemicals. Never combine acid cleaners with other chemicals.

6. Make sure air injectors are working properly and chemical concentrations are correct for your system.
Use a minimum of 160⁰F water at the start of the wash cycle and dump the water at 120⁰F. Sanitize tanks and pipelines for one hour or less with chlorine sanitizers. Check all labels of all chemicals, you might learn something important.

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7. Make sure your milk cooling system is working properly.
Chillers are necessary if you have an old tank with little cooling capacity. Ideally, if we never get milk above 40⁰F, we will have lower counts.

8. The plate cooler is a good candidate for LPC problems, lots of gaskets, etc.
If all things mentioned above fail, this is it. It should be possible to isolate the plate cooler by hooking up the inline samplers in the pipeline in front of and behind the plate cooler and run LPC’s on each sample. If the sample is high or dirty before the plate cooler, clean that part of the system and run the test again. If the sample before the plate cooler is low and after the plate cooler is high, tear it down. If neither are high and the bulk tank is high, it’s the tank.

9. Transfer hoses from the tank to the truck can be a problem also, especially on large dairies where bulk tanks are filled multiple times a day.
It is possible that the hose does not get washed and sanitized every time, causing bacterial build-up. If by chance that is due to truck dispatch problems and the tank does get washed after it is emptied, you can get milk stone build-up, which allows these bacteria to hide and slough off under the milk stone and increase these bacteria, causing LPC problems.

This is not an expensive process, just follow good husbandry practices.You might just as well get used to doing this, because these tests are going to be here forever. If you wish not to do these practices, there are dairymen in other parts of this country who will be happy to supply all the milk our processors need. PD

Excerpts from University of Florida Dairy Update, Vol. 10, No. 3

David R. Bray
Dairy Extension Agent
University of Florida

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