Effect of Preservation and Transport Conditions on SCC in Cow Milk and Losses of Precision Associated with Time Left Before Analysis

Abstract

The effect of preservation agents (without preservation, potassium dichromate, and bronopol) on the somatic cell count (SCC) of individual cow milk samples was studied at two different times during lactation. Using the fossomatic method, 1050 (experiment 1) and 924 (experiment 2) SCC measurements were carried out on milk samples from 25 and 22 cows of the same lot, respectively. In addition, each individual milk sample was divided into several aliquots and analyzed at different times postcollection (5h, and 1, 2, 3, 4, 5 and 6 days) to evaluate the loss of precision associated to each milk age, depending on whether aliquots were preserved, refrigerated, or not refrigerated. Preservation and refrigeration during milk transport had no significant effects on SCCs in both experiments, which differed in milk SCC levels. Accuracy associated to milk age depended on the lactation stage; errors were much lower when milk was more abundant and the SCC level was thus lower. For practical reasons, milk analysis for SCC should be carried out at the latest 48h postcollection.