Experience in Adaptation and Comparative Evaluation of the Coulter Counter and Direct Microscopic Somatic Cell Count (DMSCC) Method for Determining Somatic Cell Counts in Milk

Abstract

A Coulter Counter, Model ZBI, was introduced into a provincial government laboratory and adapted for use in counting somatic cells in milk. The procedure followed was a modification of the International Dairy Federation method, the main difference being in the formulation of the fixative and a slight change in diluent make-up. The procedure was further modified in operating details to enhance routine analytical work. During one year of use in the ongoing provincial laboratory program, 8130 milk samples were checked for somatic cells by the Coulter Counter. Of this number, 509 were selected at random and checked by the Direct Microscopic Somatic Cell Count (DMSCC) method. The correlation coefficient for these samples for the two methods was 0.973. The mean cell counts were 841.600 and 839,900 for the DMSCC and Coulter Counter methods, respectively. The regression formula for estimating DMSCC from Coulter Counter results was determined to be ŷ= 0.8023(x) + 163.45.