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Numerous factors can influence the levels of bacteria in bulk milk.

While there can be ‘weird and wonderful’ causes of high bactosan – the main measure of milk bacterial load in the UK – most issues are down to basic errors that can be easily identified and corrected.

See also: 7 ways to make the most of milk recording data

Below are some of the areas that the farm team can evaluate themselves.

There are three areas where errors can lead to high levels of bacteria:

Problems in these different risk areas will lead to different groups of bacteria being present in the bulk tank. Submitting samples from the bulk tank to a milk-quality laboratory will show what different bacterial groups are present and help identify which risk factors to focus on.

It is important to run these tests on several different bulk tanks to ensure the pattern of bacteria is consistent.

To avoid milk quality being compromised, focus on the following six areas of management:

Visibly dirty teats will always have high bacterial levels, but teats can also have high bacterial load when they appear clean.

There are various other options between these extremes.

Reviewing the milking process can help to reduce the risk of contamination.

Machine washing requires multiple components to be correct to ensure successful disinfection and removal of residues.

A full evaluation of the success of slug washing of the milk line requires technical expertise and equipment. However, watching to see the receiver is rattled gives a basic indication that slug transit is adequate.

A range of regular checks can help ensure milk is cooled sufficiently.

Often the biggest gains are made by improving pre-tank cooling, either by increasing plate-cooler capacity (adding additional leaves or a second plate-cooler) or by using glycol or chilled water instead of ambient water.

The following checks will highlight any aspects of tank management that need correcting:

All three main sources of bacterial contamination – milking, plant cleaning and tank management – involve water use.

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