Finding the root cause of high Bactoscan counts

As many producers well know, a high Bactoscan or total bacteria count (TBC) can lead to financial loss, increased possibility of mastitis and poor milk quality. High Bactoscan counts can be lowered, though, through proper management and regular check-ups.

The sources of bacteria in milk

There are three main sources of bacteria in milk: mastitis organisms, environmental contamination and dirty milking equipment. Contamination can occur in one of two ways: directly from the cow when mastitis organisms seep into milk, or indirectly from the environment or milking equipment.

Mastitis: Organisms that originate from the udder

Milk from cows with clinical mastitis should not enter the bulk tank, as infected milk can increase bulk tank Bactoscan considerably.  For this reason, good mastitis detection is a must.

Milk from cows with subclinical mastitis, however, will enter the bulk tank unless, of course, the farmer chooses to withhold it. The only reason to do so would be because the cow in question is known to have high cell counts. Herds with low cell counts and low levels of clinical mastitis will contribute minimal amounts of mastitis bacteria to the bulk tank. Again, good mastitis detection is a must.

Environmental contamination

For the most part, environmental contamination is caused by poor environmental conditions. Cows living in unclean environments often have dirty udders and teats. To avoid bacterial contamination, good udder and teat preparation is extremely important. On top of that, milking units should be thoroughly disinfected. Similarly, disinfected milking equipment should be attached to clean, dry teats.

Indicators of faecal contamination include coliform organisms and other environmental organisms, like Pseudomonads, Streptococcus uberis, Streptococcus faecalis and Bacillus species, among others. To avoid contamination, use a pre-dip solution and keep cows in clean, dry and well-bedded accommodations.

Dirty milking equipment

As most producers know, inadequately cleaned milking equipment can lead to raised Bactoscan. Problems can occur as a result of poor wash-up routines. After milking, all equipment should be properly cleaned. Also, the bulk tank should be cleaned after emptying.

It’s not just milking equipment that creates the potential for bacterial infection, though. Poor refrigeration has been known to cause problems as well. Milk should be cooled to 4ºC or less as soon as possible after milking. Doing so will limit bacterial growth and help to maintain milk quality.

Milk is commonly cooled using plate coolers and hear exchangers. Sometimes, though, these systems fail. Minor failures that go unnoticed can lead to big problems. A regular, thorough analysis of all milking equipment will help to avoid these types of problems. Other common problems include, but are not limited to:

• ACR flow meters that have been contaminated with milk deposits
• Water boilers set to the wrong temperature
• Maintaining temperature throughout the wash cycle
• Unclean milking units
• Deteriorating silicone tubing
• Low chemical levels in automatic wash systems

M2-magazine provided three herd case studies in its February 2015 issue. In each case, high Bactoscan and somatic cell counts were found and analysed for their causes. In each case, it was found that the bacterial outbreak was caused by one or more of the following factors: mastitis organisms, environmental contamination and/or dirty milking equipment. However, once the root of the problem was uncovered, bacterial counts returned to normal proving that, with a little work, the bacterial outbreaks are manageable.

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