Studies were made on the susceptibility to bacterial contamination of rubber milk tubes as affected by deterioration of the inside surfaces. Even with used tubes having only microscopic breakdown, contamination was much greater than with new tubes. The average contamination in the used tubes averaged 15 times as great as in new tubes under laboratory conditions and 12 times as great under practical operating conditions with dry storage. When lye storage was used bacterial counts were lower and differences were smaller. Even inconspicuous deterioration of the interior surfaces of rubber milk tubes is a potential hazard in milking machine sanitation.
aContribution No. 224 Department of Dairy Husbandry, Kansas Agricultural Experiment Station.