COMPARISONS OF MASTITIS SCREENING TEST RESULTS FROM QUARTER, BUCKET AND BULK MILK SAMPLES1,2

Abstract

Milk from four dairy farms in southern Wisconsin was examined over a period of one year in a study that was undertaken: (a) to determine the agreement between results of mastitis screening tests when applied to bulk, bucket and quarter milk samples; (b) to determine the relative efficiencies of five mastitis screening tests using direct microscopic leukocyte counts as a standard, and (c) to examine the quality, as determined by leukocyte content and screening test results, of the milk from all quarters contributing to the bulk tank on each farm. Most screening tests examined, when applied to quarter milk samples, gave a higher correlation with direct microscopic leukocyte counts than when applied to either bucket or bulk milk samples. Similarly, efficiency ratings of screening tests applied to quarter samples were higher than those for the same tests applied to bulk samples. Three of the four farms examined maintained bulk tank milk screening test scores that failed to suggest the presence of milk from a substantial number of quarters that were shedding abnormal numbers of leukocytes.