Use of the Fossomatic method to determine somatic cell counts in sheep milk

The Fossomatic method for SCC was compared with the direct microscopic method in 85 half-udder samples of sheep milk. The correlation coefficient was .986. The repeatability of the Fossomatic method showed average variation coefficients less than 5%. The carry-over effect between samples was less than 5%. The effect of the storage method (fresh milk, refrigerated at 4 degrees C and frozen at -19 degrees C) and the sample age were studied in 48 samples of foremilk and strippings. The storage method had a significant effect on the SCC variation. The average fresh, refrigerated, and frozen sample counts were 125,000, 110,000, and 82,000 cells/ml for foremilk and 201,000, 192,000, and 145,000 cells/ml for strippings, respectively. The effect of age on the refrigerated samples was also significant; counts were reduced by about 14% from d 1 to 7 in both types of milk. The effect of age on the frozen sample varied. These results suggest standardization of age and storage conditions of the milk samples to reduce variation of SCC. The milk must not be frozen.