Evaluation of Seven Procedures for Detection of Abnormal Milk Due to Mastitis

Abstract

Five screening tests (California Mastitis Test, Catalase Test, Milk Quality Test, Modified Whiteside Test, and Wisconsin Mastitis Test) and two confirmatory procedures (Direct Microscopic Somatic Cell Count and Electronic Somatic Cell Count) for testing for abnormal milk due to mastitis were evaluated for relative precision when used to test 48-hr bulk-tank milk within 6 hr after pickup, as well as 24 and 48 hr later. Because of the lack of screening test results in high- and low-count ranges, only the Wisconsin and the Catalase tests could be evaluated by statistical techniques; these procedures had replicate standard deviations of 0.73 and 2.91, respectively. of the five screening test procedures, the Wisconsin Mastitis Test gave the best indication of somatic cell numbers. A comparison of the confirmatory procedures showed the Electronic Somatic Cell Count to be more precise, with approximately one-fourth the replicate long standard deviation of the direct Microscopic Somatic Cell Count (0.012 vs. 0.047). Linear correlation coefficients of the Electronic, Wisconsin, and Catalase results with Direct Microscopic were 0.97, 0.89, and 0.70, respectively, for milks tested 24 hr after pickup. Somatic cell numbers as measured by the Electronic, Direct Microscopic, and Wisconsin procedures, but not the Catalase Test, were significantly different (α = 0.05) at each time interval tested. The effect of non-pipeline and pipeline milk filters used by milk produces on somatic cell numbers was also determined. The most efficient nonpipeline filters reduced the somatic cell count 2.5%, whereas there was no significant change in cell numbers in milk filtered by pipeline filters.