Estimating Somatic Cells in Milk Samples by the Membrane-Filter-DNA Procedure.

Further developments in the membrane-filter DNA procedure for determining the somatic cell content of milk samples are described. A statistical experiment has been done comparing the membrane-filter test to the direct microscopic somatic cell count. Under conditions of the assay a relationship of 0.093 absorbance unit per million cells was obtained at a wavelength of 490 nm. The membrane filter technique is more precise than the direct microscopic count and is not subject to techician bias. A method is described for standardizing the procedure between and within laboratories based on use of lyophilized bovine somatic cells trapped on membrane filters as a calibration device.