SOMATIC-CELL COUNTING IN MILK - PERFORMANCE OF THE ANADIS SCC AND COMPARISON WITH THE FOSSOMATIC-360 SYSTEM

The number of somatic cells is an important quality parameter for raw milk and an indicator of hygiene and the mastitis situation as well. F or the instrument Fossomatic 360 (fluorescent-optical principle) a lar ge number of usable empirical data has been published. Therefore, the latter was used to conduct comparative trials with the Anadis 500 SCC (fluorescent-optical measurement, flow cytometry). For measurements us ing 402 quarter foremilk samples, a coefficient of correlation of 0.99 4 was found; after logarithmic scale transformation it is 0.976. After square-root transformation the coefficient of correlation is 0.995. A good agreement of the measuring level holds for values of up to 1.2 m illion mi; only values exceeding this limit lead to an underestimation of the Anadis. A good agreement of the results is ensured with the pr eservatives potassium dichromate, Bronopol and boric acid. Lower value s are obtained, if sodium azide or cooling are used. For potassium dic hromate, Bronopol and boric acid, a shelf life of 2-3 d is given. The carry-over (<3%) is very small. In the course of a few days no serious problems were encountered with the stability of the instrument. Withi n the range between 400 and 500,000 cells/ml deviation is less than 6% . Counting precision is good. In the range below 100,000/ml the absolu te error reaches not more than a few units. Within the range of 100,00 0 and 500,000/ml the relative error is 3%, in the range exceeding 500, 000/ml it is less than 3%. A first intercomparison has shown, that the instrument allows good results to be obtained. A continuous calibrati on should be carried out by means of reference samples (''standards'') .