All Pasteurized Waste Milk Is Not Created Equal

A decades-long study of on-farm pasteurized waste milk conducted by Land O’Lakes (LOL) Animal Milk Products Company shows gaps in nutrition, pasteurization kill rate and residual antibiotics.

The study, conducted from 2006 through 2017 on 618 U.S. dairy farms, looked at herds raising from 5 to 5,000 calves. Milk samples, taken immediately after pasteurization, were collected for seven consecutive days from each farm and then sent in for analysis.

Fat content of the milk showed an average variation of 17.3% within farms, protein varied 7.9% and total solids varied 6.6%. This variation can come from using waste milk from cows in different stages of lactation and health status. “This high level of variation makes it challenging to provide a consistent, nutritious diet to young calves,” says Tom Earleywine, director of nutritional services for LOL Animal Milk Products.

On-farm pasteurization also failed more than 40% of the time on these farms when milk was tested for bacteria immediately after pasteurization. Only 58% of samples had less than 20,000 colony-forming units (CFUs) immediately after pasteurization. And only 46% had less than 20,000 CFUs in sample taken after the last calf was fed.

Since the waste milk used to feed calves usually comes from treated cows, residual antibiotics can also be a concern. In the LOL study, 57% of the samples contained traces of antibiotics. Other studies have shown an increase in antibiotic resistance in calves fed waste milk compared to those fed milk replacer,

You can read the entire study here.



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Submitted by Sandra Godden, Professor, University of Minnesota on Wed, 01/03/2018 - 12:06

Regarding the Dairy Herd Management Article: “All Pasteurized Milk Is Not Created Equal”

This article summarizes the results of an 11-year observational study, the objective being to describe bacteria levels and nutrient composition in pasteurized milk on commercial dairy farms. The authors conclude that “Pasteurized waste milk is a highly variable source of nutrition for dairy calves and on -farm pasteurization does not consistently deliver waste milk with a low bacteria count”. This is true on many farms. There is certainly lots of room for improvement for many farms to enhance monitoring and management of these systems. However, I do have some serious concerns with the methodology that was used to determine the bacteria counts in pasteurized milk in this study:

Concern 1. Failure to freeze milk samples. The milk samples were apparently refrigerated (not frozen) for up to 7 or more days on the farm, before being transported to the lab for testing. We know that bacteria will multiply in refrigerated milk, with a 1 to 2 log increase observed in 2 to 6 days after storage in a refrigerator. As such, the bacteria levels reported in this will be significantly (and artificially) higher at time of testing in the lab than at point of collection on the farm. Samples should have been frozen.

Concern 2. Flow cytometry, not aerobic culture, was used to determine bacteria counts in pasteurized milk. Flow cytometry (FC) is recognized as the standard method for doing bacteria counts in RAW MILK. However, FC is NOT an appropriate test to use for bacteria counts in pasteurized milk, namely because it will pick up dead bacteria. Furthermore, flow cytometry counts will not equate/correlate to traditional aerobic culture results (e.g. total plate count; TPC) for several reasons including the following: i) FC will count anaerobes, ii) FC will count dead bacteria, iii) FC will count psychotrophes, etc., and iv) FC will break apart clumps and be able to count multiple bacteria that would otherwise be counted only as a single cfu if doing culture. And so my concerns with use of FC as the test method to count bacteria are two fold:
i) The FC test is inappropriate to use on pasteurized milk, as it will have counted dead bacteria along with living bacteria, thereby increasing the apparent counts in pasteurized milk.
ii) For the many reasons mentioned above, FC results will NOT equate to traditional aerobic culture (TPC). As such, the same goals for cutpoints would not be applicable to FC results (e.g. TPC<20,000 cfu/ml or < 100,000 cfu/ml.)

So to sum up, because milk samples were not frozen, and because fly cytometry was inappropriately used as the test method to determine bacteria counts, the bacteria count data reported in this study are highly suspect and probably invalid.
This does not mean that farms should ignore this concern. Many farms could do a much better job of monitoring and management their pasteurization systems. I encourage producers to work with their veterinarians to set up such monitoring schemes.

Submitted by Melody Cowan on Wed, 01/03/2018 - 13:08

Thank you for this added information. I am always suspect on these trials, especially when they are paid for by someone who will profit from us changing what we do ie Land O Lakes sells milk replacer. We have a seasonally calving herd and pasteurize the waste milk and tank milk mixed in when waste is not enough. We raise jerseys and have been pasteurizing for the past 10 years. This past year was the best yet with one calf lost due to circumstances beyond our control. I raised over 700 calves to weaning. We haven't weighed at weaning for a few years but out weaning weight at 8 weeks was around 135lbs. I have not ever tested our pasteurized samples as I have extremely healthy calves so see no need. Maybe this year I might. But what I see is everyone throwing money at a problem and no one just looking at how to properly apply the basics. I do agree that if you only had a few cows waste milk it could throw everything off so smaller herds could have potential problems.

In reply to by Sandra Godden,… (not verified)

Submitted by Tom on Thu, 01/04/2018 - 22:03

Thanks to Dr. Godden we discovered our report had inaccurate information and some that was misinterpreted. We mistakenly reported that we used flow cytometry to look at bacteria counts but actually plate loop counts were used which would only measure live bacteria. Flow cytometry was only used for somatic cell counts.

Secondly we did not freeze samples which, depending on methods, can reduce counts substantially. However the samples were properly cooled and arrived at the lab within 1-2 days of collection.

Sorry for any confusion caused.

Our main purpose of this study was to look at the consistency of nutrition provided by waste milk. Our secondary purpose here is, as Dr. Godden pointed out, to hopefully get more dairies to do a better job pasteurizing their calf milk and monitoring that process. As you would suspect, some dairies had excellent results in both areas!

In reply to by Sandra Godden,… (not verified)

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