Current Progressive Dairy digital edition

Milk quality is everyone’s responsibility

Jessica Belsito Published on 31 December 2013

Imagine this scenario: You produce high-quality milk. You take pride in receiving your quality premiums for low preliminary incubation (PI) counts. Your system is clean, you use high-quality chemicals in the right amounts, and you check that your wash cycles are running correctly on a regular basis.

One day, out of the blue, your creamery gives you a warning that your PI counts are getting too high. You are having erratic counts. One minute your PI count is at its normal level, and the next it has skyrocketed into unacceptable territories.



So you shock your system. Take it all apart. Inspect every inch for biofilms and check every rubber gasket for residue and cracks. Still your PI counts are too high. It can’t be your bulk tank because you load your milk right into a milk truck.

You try new chemicals, then a new chemical supplier. Nothing is getting better, and now you have lost your premiums. A frustrating situation just turned into a financially stressful one. The creamery tells you it is your fault. Surely it is not theirs. Their tankers are clean, and they hold milk at the proper temperature. So the problem is on your farm. Surely.

This scenario has happened in the past. Time and money were spent trying to solve the issue. Nothing could be found in the milk line. The chemicals were being used appropriately.

Everything was checked, rechecked and triple checked. Everyone involved was frustrated, stressed and confused. Finally, the dairyman realized the problem might not be on the farm.

Despite what the creamery claimed, maybe the problem was with the milk truck or at the lab. What were the creamery’s sampling protocols? Were the samples being handled correctly? And perhaps more importantly, when was the sample taken?


The dairyman’s first step in solving the puzzle was to begin taking his own samples. Armed with some sterile collection jars and a cooler with ice, he began taking daily samples from the drip line before the milk entered the tanker. He then took these samples to an independent lab to have PI counts determined.

The counts were low, as they had always been on that farm. He continued to repeat this process until he could be sure there was no mistake. The creamery and his lab where getting two drastically different results. But why?

A trip to town on Sunday may have led him to his answer. There was a milk truck in the milk hauler’s driveway. Was he picking milk up and letting it sit? And how long was he letting it sit for?

The creamery’s answer to this was, “Even if the milk did sit, it is still being maintained at the correct temperature inside the tank.” That may be true, but what about psychrophilic bacteria (or cold-tolerant bacteria) that are able to grow in refrigerated conditions?

These bacteria may be able to multiply in milk held at 45ºF and can multiply rapidly in milk held at 55ºF. The PI count is the tool we use to determine the amount of these bacteria in the milk. This count is one tool used to determine milk quality.

This dairyman was being told he had high PI counts. Yet the samples from his drip line yielded low PI counts. We know the milk truck was sitting in the driver’s yard over the weekend.


By law, the milk in the truck must be below 45ºF, and any samples must be held at 40ºF. We also know that psychrophilic bacteria may be able to multiply in milk at this temperature, and multiplies rapidly at 55ºF.

It took many weeks. But finally the dairyman was able to prove to the creamery that his milk was not to blame. The fact that his milk was sitting around for 48 hours before the samples were drawn was the problem. This 48-hour window gave the bacteria a chance to multiply before the samples were incubated for the PI counts.

What does this mean for you and your farm? It means that you need to be familiar with the sampling, storage and handling procedures of your milk as well as the quality standards your creamery or co-op enforces.

The federal government does not regulate PI counts, and therefore acceptable PI counts and premiums based on the PI count can vary. It is also prudent to be sure the sample is being taken immediately, the proper protocols are being followed, and the sample is being stored at the correct temperature.

These sampling protocols are regulated by the government and are laid out in the Pasteurized Milk Ordinance, which can be found online on the FDA’s website.

If you think the sampling procedures your milk hauler, creamery or lab are using are to blame for a quality problem, there are independent labs you can bring a milk sample to for a “second opinion.” Just make sure you follow milk sampling procedures carefully yourself. Don’t let someone else’s errors rob you of your quality premiums. PD


Jessica Belsito
Director of Marketing and Technical Adviser
IBA, Inc.