Understanding somatic cell counts

Measuring somatic cell counts help control mastitis and improve milk quality in your herd by identifying infected animals that need to be treated or culled.

Somatic cells explained

Somatic cells are mainly white blood cells that increase in number in response to the bacteria that cause mastitis. Somatic cells are always present in milk. They only cause concern once  a cow has between 120,000 and 150,000 somatic cells in every millilitre of milk it produces. The higher the somatic cell count the worse the infection.

High somatic cell counts mean lower production

Cows with high somatic cell counts usually produce less milk than those with lower counts. They may also be less fertile. 

The earlier you identify and treat infected cows the more productive your herd will be.

High bulk milk somatic cell counts can lead to penalties

Just a few infected animals can increase the bulk milk somatic cell count in your vat and put you at risk of being penalised by your dairy company. 

Regular herd tests help keep your bulk milk counts at an acceptable level by identifying individual animals with high somatic cell counts that may need treatment or culling. 

Detect sub-clinical mastitis

Somatic cell counts identify cows with sub-clinical mastitis. Unlike cows with clinical mastitis, cows with sub-clinical mastitis show no physical signs of infection but they are often less productive. They may also infect other animals in your herd.

Regular herd tests help prevent sub-clinical mastitis from becoming a problem in your herd. 

Reliability of somatic cell counts

Classic tests (afternoon and morning sampling) produce the most reliable somatic cell counts. Afternoon samples have higher concentrations of somatic cells than morning samples as there is a shorter interval between milkings. Averaging the somatic cell count of the two samples provides the most accurate 24-hour somatic cell count. 

Full results are most reliable for single tests

Single tests produce slightly different somatic cell counts depending on when they are taken.  If you milk twice a day the counts are slightly lower in morning samples and slightly higher in afternoon samples.

A day or so after the test you will receive a preliminary report called a Lab Strip. It includes all the raw data from the test, including the actual number of somatic cells in every milk sample. 

If you milk twice a day and choose a single test, we recommend waiting for the full herd test report before deciding which animals to treat for mastitis. 

The full report should arrive within four days of the test. It includes a 24-hour somatic cell count for every animal in your herd.