Scanning electron microscopy was used to examine microorganisms on the skin of cows' teats which were artificially contaminated and subsequently stored for different times. From the results it seems that bacteria were not spread uniformly on the surface of the teats. No extra-cellular polymers were observed before storage of the teats, but during storage polymers, in the form of thin fibers, were produced. These fibers became thicker and finally resulted in slime. Multiplication of bacteria during storage involved formation of microcolonies of bacteria in which bacteria were not attached directly to the skin but to other bacteria. This explains the decrease in the differences between bacterial counts obtained by the blending and rinsing methods after long periods of storage.
2Public Health Institute.
3Technical and Physical Engineering Service.