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Adjustments to protein testing, effective Sept. 1

August 21, 2018

Dairy Farmers of Ontario (DFO) will be changing protein testing from total protein to true protein, effective Sept. 1. The true protein test will be used for processor billing and producer payment.  

This change will result in protein tests decreasing on average by 5.5 per cent. However, the difference will be recaptured in the lactose and other solids (LOS) test. On average, this change will be revenue neutral to producers since the price charged to processors will be adjusted accordingly.


The current protein test used for billing and payment measures crude protein in milk, which is also called total protein. The difference between crude protein and true protein is non-protein nitrogen (NPN). On average, NPN accounts for 0.19 kilograms per hectolitre, or 5.5 per cent of the protein test.

About 50 per cent of NPN in milk is urea, and there is a variation in NPN that is primarily attributed to the variation in urea content. This variation can be influenced by farm management, feeding practices and seasonality. NPN has little nutritional value and doesn’t contribute to cheese yields, which means it doesn’t have the same economic value as true protein.

True protein has been used as the official test for payment in the United States since January 2000.

Why are the tests changing?

During negotiations with processors, it was agreed to use true protein testing. When milk protein concentrates (MPC) are manufactured, NPN is filtered resulting in losses of MPC. By no longer counting NPN as part of protein, it eliminates losses that need to be accounted for during the filtration process. True protein from milk is retained in MPC. This resolves the issue over how protein losses are accounted and paid for between producers and processors, and equity between processors.

What is changing?

All official labs for payment will switch to true protein testing for Sept. 1 samples. The protein test will decrease by 5.5 per cent—the amount of NPN in the sample. This amount will be captured in the LOS test, meaning the change will be revenue neutral between producers and processors.

Next steps

The lab will start testing September samples on Sept. 5 for true protein. Canadian Lab Services will conduct a study over the next year to confirm the 5.5 per cent price conversion is reflective of the actual NPN in Canadian milk. If a further price adjustment is required, it will be made in February 2020.

CanWest DHI testing will continue to be done on a crude protein basis. As a result, DFO’s protein testing for payment and DHI’s testing will not measure the same protein.

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