Finally it may be from bacteria buildup on inadequately cleaned milk contact surfaces anywhere in the system. Milk cooling problems may also contribute to elevated bacteria counts because warm temperatures accelerate bacteria growth. T he objective is to keep raw milk bacteria counts as low as possible and when problems occur each of these issues has to be considered. Typically such bacteria originate from sources outside the udder. It may be possible for certain Strep non-ag bacteria to also elevate the PI when they are shed from infected quarters, but typically, elevated PI counts are linked to external sources, not infected cows.
Water contaminated with Pseudomonas species is often the source.
It may be stagnant water that cattle have access to or contaminated hose water used in the parlor. F ailure to cool milk adequately and quickly during and after milking provides favorable conditions for these bacteria to grow. Old, cracked rubber tubing, especially around milk inlet locations, is a place where these bacteria may collect and build up. B etween milkings, bacteria in soil films on equipment surfaces may continue to grow and cause PI problems. Sanitizing system components prior to milking will kill most bacteria while failure to sanitize will allow them to go directly into the bulk tank and create problems.