Effects of Milk Storage Duration on Various Tests for Abnormal Milk

Abstract The influence of age of Schiff's reagent on the response of the Feulgen-DNA mastitis test was determined in an initial experiment. The average reflectance Feulgen-DNA values were always higher (indicating less DNA) in aged than in fresh Schiff's reagents, and this difference usually increased with each increase in age of the reagents. The Schiff's reagent should be discarded after 2 wk, when the color intensity is determined by reflectance spectrophotometry, or after 3–4 wk when the color is scored against a Standard color chart. The pH, California Mastitis Test (CMT), Milk Quality Test (MQT), Michigan Mastitis Test (MMT), catalase test, and reflectance Feulgen-DNA test values were determined on 40 milk samples after zero, one, two, three, and four days of storage. The CMT, MQT, and MMT gelation tests declined 0.5, 0.6, and 0.5 of a score, respectively, between Days zero and four. The pH, catalase, and reflectance Feulgen-DNA values were unaffected by the four-day storage period.