Tuesday, December 19, 2017

Pasteurized Milk for Calves and 
Murphy's Law
(If anything can go wrong, it will go wrong!)

"If anything go wrong, it will go wrong" That's the so-called Murphy's Law. Or, sometimes it comes out as "If anything can be done wrong, someone will find a way to do it wrong!"

In a recent study of pasteurizing milk for calves on 618 dairy farms in the US the results were not good for calves. 

Bacteria counts immediately post-pasteurization:

Really Bad (% greater than 100,000cfu/ml)        27%
Poor (% between 20,001-100,000cfu/ml)            14%
Good (% less than and equal to 20,000cfu/ml)    58%

To put these numbers in context, the threshold for adequate pasteurization of milk for feeding calves I use for my clients is 5,000cfu/ml total plate count, 1,000cfu/ml coliforms.

Unfortunately, this study did not report bacteria counts for the raw milk going into the pasteurizers. So we don't know for sure the problem was poor pasteurizer performance, poor pasteurizer cleaning or excessively contaminated raw milk. 

They did report percentage of contaminated milk samples by type of pasteurizer (contaminated defined as greater than 20,000cfu/ml).

Type of pasteurizer:                      Percent of Samples
                                                      Greater than 20,000cfu/ml
High Temperature/Short Time              38%
Batch pasteurizer                                  37%
UltraViolet treatment                            47%

Again, since the study did not report bacteria counts of raw milk going into the treatment units we cannot estimate accurately the efficacy of the units. 

Reference: Yoho, W.S.B, and Others, "Variation on nutrient content and bacteria count of pasteurized waste milk fed to dairy calves." American Journal of Dairy Science Supplement T132, 2017.

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