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Managing Bulk Milk Cell Counts

High bulk milk cell counts (BMCC) can be a source of great concern for dairy farmers wanting to optimise their returns from milk produced and lower the level of mastitis in their herd.

The prime cause of increased cell count in an individual cow is bacterial infection in the udder or, in other words, mastitis. Once an infection occurs, the cow sends her defence cells (white blood cells) to the udder to fight the infection. These are the cells that are measured in a cow’s individual cell count.

Individual cow cell counts measure the level of mastitis infection in the individual cow.

The BMCC is a combination of the individual cell counts of all the cows in the herd and measures the level of mastitis infection in the whole herd. BMCC increases when mastitis levels increase, which can be due to missed clinical cases or subclinical cases of mastitis.

Estimating the level of mastitis in a herd using BMCC (Ryan, 1991)

BMCC (cells per millilitre)

Rough estimation of percentage of cows with a mastitis infection (sub-clinical or clinical)







Mastitis is a multi-factorial disease, meaning there is a large number of factors that can contribute to a high BMCC or a high number of clinical cases. There is a process to follow to identify key areas that are leading to a high BMCC.

The Countdown mastitis investigation process

Countdown has a well-established process which involves using farm data (BMCC and herd test information) combined with taking milk samples from the problem cows (such as recent high individual cell count cows). These samples are then sent to a laboratory be cultured in order to identify the type of bacteria causing mastitis spread on the farm.

Depending on the results of the milk cultures, areas for further investigation can be prioritised by working with a Countdown advisor, such as:

  1. Dry-off management
  2. Calving management
  3. Lactation
  4. Milking machine performance
  5. Milking procedures, including teat disinfection and management of clinical mastitis cows
  6. Environment
  7. Culling

Countdown resources

Countdown technotes and farm guidelines relevant to managing BMCC are available to help dairy farmers.

Fact Sheet R, The benefits of lowering bulk milk cell counts, contains information about the increase in income with decreasing BMCC despite being below the premium offered by milk processors.

Whilst understanding and reducing where mastitis is spread is key to lowering BMCC over time, the High cell count cows – what are the options article discusses options for managing the impact of high cell count cows.


  • Technote 11 Monitor Bulk milk cell counts

    PDF241.58 KB
  • factsheet R Benefits of lowering BMCCs

    PDF60.77 KB
  • High cell count cows - what are the options?

    PDF233.39 KB
  • Countdown Farm Guidelines 11 and 12

    PDF109.25 KB

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