Accuracy of a Lactometric Field Test for Measuring Solids-Not-Fat Content of Milk

Abstract

Long dash]The solids-not-fat (SNF) content of milk can be measured with sufficient accuracy in the field by DHIA supervisors using the small Watson-pattern lactometer if readings are made at 102 [plus or minus] 0.5[degree]F. In the first of 2 trials, comparisons between field and laboratory measurements showed small differences due to improper temperature control. No practical differences between field and laboratory were observed in the 2nd trial. The mean difference between lactometer readings in the field and in the laboratory was 0.28 lactometer degree. Accuracy to 0.5 lactometer degree is comparable to the accuracy of the Babcock test for fat. Correlations between field and laboratory tests, between duplicate samples in the field, and between duplicate samples in the laboratory were .96, .98, and .98, respectively, for the first trial, and .97, .99, and .99, respectively, for the 2nd trial.