Milk Quality – High Bacteria Counts

The time of whatever is legal is OK is ending. Our processors are demanding more quality and not necessarily paying for that quality. While this may not seem fair, that’s the way it is. Producing milk with low Standard Plate Count (SPC) is quite easy and just takes attention to details. Bacteria counts are a function of three things: cleaning, cooling, and cows, and usually in that order.

Cleaning: Cleaning a milking system should be simple. Just do it the same way every milking. This works real well if the same people do it every milking, but in most cases this is not the case; help changes, chemicals change, things wear out or quit working and the changing help does not know that. If you can’t speak the same language as your help, it’s hard to make changes, what can change:

     1- Bought new cleaning chemicals, this is a better buy, $50 less a drum, only instead it calls for 1 ounce of
          chemical per gallon of water and the old chemical called for 1 ounce per 5 gallons of water, so you need
         60 ounces rather than 12 ounces. And to make things worse the guy who delivered this did not leave
         any instructions on the wall on how much chemical to use, the sales person should be flogged. You
         must use the correct concentrations of soap, acid and sanitizers.

     2- Do you know how much water your wash sink holds when full? Most old half round long sinks hold about
         a gallon per linear inch, a 60” sink holds about 60 gallons to the fill line, do you have to add extra water
         to the sink so it does not go dry, and that water must be accounted for also. Does anyone know how
         much water is added to the bulk tank wash cycles? And how do you add two little bottles of soap to the
         tank washer?

     3- Hot water is necessary to clean a system, not to rinse a system. If you can get a good rinse with cold
         tap water you will save energy. If you have a 50 gallon hot water heater, a 60 gallon pipeline wash
         sink and need 100 gallons of hot water to wash the bulk tank, you better stage your procedures. At
         least 160° water is needed to start the soap wash–up and the solution should be dumped when the
         temperature drops to 120°, acid rinse can use tap water.

     4- Sanitization cycle using chlorine should be done 30 minutes or less before the start of milking. For the
         pipeline and bulk tank, some acid rinse\ sanitizers can be used at longer intervals. Be sure to follow the
         directions on all chemicals.

     5- The air injector is an important part of the wash up system and needs to be adjusted to get the proper
          slugging to clean the system; this seems to be a common play toy for the help so inspection is often
         needed.

High bacteria counts often mean that it is time to change all milk hoses, wash up hoses, jetter cups. All rubber
and plastic hoses should be replaced every six months. Silicone hoses should be replaced according to
directions. The milk pump may need to be dissembled and cleaned, the main vacuum and pulsation lines should
be flushed. If all else fails take apart the plate cooler and clean it and reassemble with new gaskets. The positive side of the system, from the milk pump to the tank is the hardest part of the system to clean because it does not get the slugging action of the vacuum side.

Cooling: Make sure you follow the directions for the particular tank for when to start the tank before the
milking process. Most dairies have some sort of pre coolers for the milk anyway. It is important to keep the
outside cooling fins free of dust and dirt to get proper cooling. Low coolant is also a major cause of warm
milk.

Cows: If you have an elevated Somatic Cell Count (SCC) you can have a high bacteria count also, but this
is not necessarily true. Strep uberis infected cows may shed high numbers of bacteria and several cows can
elevate the SPC. A cow with a problem should be handled like a high SCC cow. Find your high cows and deal with them.

By David R. Bray
Dairy Update newsletter - University of Florida
Department of Animal Sciences - Institute of Food and Agricultural Sciences