The Direct Microscopic Somatic Cell Count can be used advantageously in control of abnormal milk to perform simultaneously screening and confirmation of milk samples. Confidence limits computed according to the individual microscope Strip Factor are used to interpret the count made on a single strip of one of the two milk films. The sample is assigned on the basis of the interpreted count to one of three categories: (a) less than the legal cell concentration maximum ( P <0.05); (b) in the region of the cell concentration maximum and thus subject to confirmation; or (c) greater than the legal cell concentration maximum (P <0.05). For samples in categories (a) or (c) no further counting is required to accept or reject the milk. For samples in category (b), the four-strip confirmatory count may be completed immediately.

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Author notes

1A contribution from the Subcommittee on Screening Tests, National Mastitis Council, Inc.

2United States Department of Agriculture, ARS, Animal Science Research Division, Beltsville, Maryland 20705.

3Department of Clinical Pathology, School of Veterinary Medicine, University of California, Davis, California 95616.

4Statens Veterinaere Serumlaboratorium, 4, Odinsvej, DK 4100 Ringsted, Denmark.

5Department of Veterinary Microbiology and Immunology, Ontario Veterinary College, University of Guelph, Ontario, Canada.

6Department of Large Animal Medicine, Obstetrics, and Surgery; New York State Veterinary College; Cornell University; Ithaca, New York 14850.

7Laboratory Division, State Department of Health, P. O. Box 1689, Hartford, Connecticut 06101.