Somatic Cell Content Variation in Fraction-Collected Milk

Abstract

Total milk somatic cell content of various fractions of milk collected during milking were estimated by reflectance Feulgen-DNA, to determine which portion provided the best estimate of the number of somatic cells in primary milk, and to attempt to better understand the cellular variation in various fractions of milk. The first five fractions did not differ significantly (P > 0.05) from primary milk, but strippings and complementary milk each contained significantly (P < 0.01) more somatic cells than primary milk. Correlations between total somatic cell content in each fraction with the total somatic cell content in primary milk ranged from 0.91 to 0.97. The data indicated that any of the fractions used in this experiment could be used to predict the number of somatic cells in primary milk. Direct microscopic counts of fraction-collected milk indicated that granulocytes constituted 66.4, 68.5, 66.8, and 69.2% (P > 0.05) and mammary epithelial cells 27.6, 24.9, 24.3, and 21.1% (P < 0.01) of the total somatic cells in the first 20-ml, ninth 20-ml, strippings, and complementary milk, respectively. © 1966, American Dairy Science Association. All rights reserved.