Babcock is accurate to plus or minus 0.1, while Mojonnier is accurate to plus or minus 0.03. Preservatives, depending on the length of time between sampling and testing and the environmental temperature, can alter the test results. Therefore, the difference obtained with a preserved sample and a fresh sample can vary by as much as plus or minus 0.1 percent. However, a difference this large rarely happens. Improper sampling technique by either your DHIA supervisor or bulk tank sampler or improper use of DHIA meters or low vacuum on DHIA sampling day can cause the greatest discrepancies in test results.
Proper agitation corrects many problems.
If you believe the DHIA supervisor is taking the sample improperly, contact the DHIA region manager. If you think the problem is caused by the bulk tank sampler, call the dairy plant field representative. Be prepared for a change in your milk check if a problem is found. Frozen or heated samples can alter fat test results in ways that researchers cannot fully explain. Preliminary studies show frozen samples tend to have depressed fat test results, perhaps related to the thawing method and how much churning occurred after thawing.