Veterinarian: Low Counts Means High Milk Quality
Published: Friday, February 16, 2018
"Every dairy can make quality milk. You just have to decide to do it," said Dr. Brandon Treichler, D.V.M., quality control veterinarian, Select Milk Producers, during the 2018 Great Lakes Regional Dairy Conference.
One bacterial cell can replicate once every hour. In a 24-hour period from just one bacteria cell, a yield of 17,000,000 cells is possible under optimal conditions. Results from required testing can help farmers pinpoint problems within the system, correct them through maintenance or procedure changes and provide a monitoring tool to address problems.
"In the future, I think there will be less incentive from the processor to pay for quality," Treichler said. "We will have to transition to a mindset that low quality milk will be a barrier to market."
Bacteria in the milk derives from three sources: residues in milking system, from the cow herself through mastitis, or from the environment in dirty equipment, filters and contaminated teats. Each has its own desired temperature in which to thrive. Bacteria in the system prefers 130 degrees F while mastitis pathogens prefer the cow's body temperature of 101.3 degrees Cool temperature bacteria prefer 50 degrees to thrive.
The Standard Plate count (SPC) test estimates bacterial populations in milk and is required by the Pasteurized Milk Ordinance (PMO). However, SPC doesn't indicate the contamination source or give a complete analysis of all bacteria types present. The federal PMO legal limit is 100,000 cfu/mL, however, many co-ops require less than 50,000 cfu/mL and SPC's of less than 1,000 cfu/mL is achievable.
The Lab Pasteurized Count (LPC) selects for bacteria that survive pasteurization. Elevated LPC indicates a problem within the CIP wash and system buildups. Pasteurization kills mastitis and coliforms, but leaves the heat tolerating bacteria, many of which form spores which protect the bacteria through the drying and powdering processes. Powdered milk is often graded by spore counts, and high spore levels won't find a spot in high revenue markets.
If specific bacteria strains can't be identified from PIC, what can the numbers reveal?
One rule of thumb, according to Treichler, is if the PIC is three times greater than the SPC, there is a problem caused by psychotropic bacteria which grow at cool temperatures. This ratio indicates a problem within cooling functions that often come from bulk tanks, milk silos or plate coolers, worn or dry rotted rubber components, leaking plate cooler gaskets or flushing lines with water at the end of a milking shift.
A special growth media is used to incubate for coliform bacteria that comes from manure. Coliform counts between 100/mL and 1000/mL indicate poor udder prep in the parlor. Counts greater than 1000/mL may be a sign of bacterial growth within the milking system itself.
Correct application of temperature, chemical and mechanical actions are the foundations of a thorough cleaning.
Water temperature greater than 120 degrees is required to turn fat into liquid and suspend it. Water temperature higher than 185 degrees bakes milkfat onto system components. Water is the most important component of the CIP wash, as it is the universal solvent and carrier for the remaining products. Softened water may solve many cleaning system issues.
The alkaline detergent breaks down fats and carbohydrate components of milk residue. The acid component reacts with mineral or milk stone component and the chlorine compounds denature protein and sanitize milk contact surfaces.
The mechanical or turbulence part of the washing must have enough time contact with all the surfaces and wrap around the receiver to contact all surfaces including traps.
In the end, Treichler says that clean cows with clean teats and lots of hot water will take farms far in controlling bacteria and keeping counts low for high quality milk.
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