Influence of Milk Sample Agitation on Abnormal Milk Test Scores

Abstract

When raw milk is routinely tested for mastitis-caused abnormality, the test is usually performed on milk samples that have been previously shaken for bacteriological testing. The effect of this agitation on Wisconsin Mastitis Test, Direct Microscopic Somatic Cell Count, and Electronic Somatic Cell Count scores was evaluated with the use of 48-hr bulk-tank milk samples. Shaking did not affect the Wisconsin Mastitis Test and Direct Microscopic Somatic Cell Count scores, and the scores were stable through at least three shaking series. Precise Electronic Somatic Cell Count scores depended on the milk sample being shaken (25 times through a 30-cm arc within seven seconds) before preparation for counting because, after the sample had been agitated by one shaking series, the Electronic Somatic Cell Count increased significantly over that obtained when the samples were agitated solely by inversion. Subsequent shakings had no further effect on the Electronic Cell Count.