Somatic Cells

Somatic cell score (linear score)

To perform the categorization of milk somatic cell count, producers use the linear score. This standard has been adopted since 1982 by the National Cooperative Dairy Genetic Improvement Program (DHI), in the United States. 

These parameters are of paramount importance to understand the relationship of somatic cells as well as the result of the production of cows and herds.

Categorization by CCS of the herd's total milk shows that alterations of a small number of cows do not strongly interfere with the mean score of the herd.

A noted observation is that the production loss of each cow in a herd with a linear score 3 was approximately the same as the loss of an individual cow with a score 4.

To obtain the score, mathematical calculations are performed (logarithmic transformation). Thus, CCS values (typically several thousand) are transformed into 10 categories from 0 to 9. 

See the table below for the classification of scores in relation to somatic cell count:

What is somatic cell counting used for?

A contagem de células somáticas é uma importante ferramenta na avaliação de diversos aspectos do rebanho, mas também do negócio. Entre eles, podemos citar o monitoramento na qualidade do leite, fertilidade, bem como o indicativo da estimativa de perdas quantitativas e qualitativas da produção.

The somatic cell count (SCC) does not always indicate that a cow is suffering from an infection. This conclusion is due to the fact that the types of leukocytes in milk vary with a number of factors. Thus, the lactation stage, time of year, diurnal variation, milking frequency and intervals, number of lactations and the animal's stress level are included in the analysis. 

Increased CCS indicates an immune response most commonly linked to infection, however it is also part of this immune response and confers some protection to the animal.

SCC is expressed as the amount of somatic cells per ml of milk and can be used as an indirect measure or health indicator of breast health. That's because most somatic cells are made up of immune cells that are produced in greater numbers by an infected gland.

In this context, the monitoring of CCS is extremely important, since the increase contributes negatively to the increase in costs, among them, those arising from drug treatments, milk disposal, changes in milk composition and loss of bonus payments from milk to dairy products. It is worth noting that the greatest cost of this process is precisely the cost of discarding the milk.

Furthermore, in cases where SCC remains chronically high (> 200 thousand cells/mL), the tendency is for the cow to be discarded from the herd, due to the difficulty in curing infections and the very high chance of reinfections and contagion of healthy cows in the herd. Thus, this is another negative impact of the increase in SCC and which should be used as an indicator of milk quality management and cost reduction and control.

What is the impact of somatic cells on bovine fertility?

It is true that the increase in the calving interval directly affects the production of cows in a negative way. Therefore, producers seek to maintain a faster pace to impregnate the cows as quickly as possible after the voluntary waiting period, reducing the so-called "open period".

What do runaway somatic cells have to do with bovine fertility?

Well, several factors that delay the new pregnancy of cows during lactation, stand out inaccuracy in the detection of heat, conception failures and pregnancy losses. In the last two cases, the occurrence of mastitis tends to be a major influencer.

Therefore, it is extremely important to take into account the health of the mammary gland also with regard to reproductive management. This is because herds with a high incidence of mastitis tend to have lower fertility and therefore higher costs and lower profitability in milk production.

Studies carried out by the GERAR Leite group (Group Specialized in Reproduction Applied to the Herd) in 2020 show that cows with high CCS have lower fertility at TAI and TETF, in addition to greater pregnancy loss. 

Furthermore, cows with somatic cell counts lower than or equal to 200.000 cells per mL of milk had a pregnancy rate at first TAI 14% higher than that of cows with SCC between 200.000 and 400.000 and 22,6% higher than the rate of cows with CCS above 400.000.

Control of cell count in lactation

It is possible to take measures to prevent and combat infections during the cow's dry period. This is done to contain the increase in somatic cell count during lactation, as well as to provide preventive therapy for mastitis.

Assim, o produtor pode utilizar antibióticos intramamários de amplo espectro, que se destacam por sua eficácia contra agentes contagiosos, ou, contra agentes ambientais, fazendo uma proteção mais completa. Além disso, outro grande aliado no período seco é um selante químico que, de forma mecânica, bloqueia o acesso de micro-organismos à glândula mamária, ajudando no bloqueio de infecções e também sendo auxiliar na ação das terapias de vaca seca.

The veterinarian is the competent and legally qualified professional to make this type of prescription and help the producer in this step.

Somatic cell count (SCC) as an indicator of milk quality

With the constant demands that are imposed on dairy producers, they have been looking for ways to measure the quality of milk, reduce their costs and increase the profitability of milk production.

In this way, these producers seek to carry out actions that guarantee the framework of dairy products in the legislation to remain competitive in the market.

Thus, it would be impossible to improve the quality of care for their cows if they did not have an effective measure to determine positive and negative changes to improve milk quality.

Therefore, counting the number of somatic cells has become the standard method of measuring milk quality. Therefore, CCS is one of the main indicators of milk quality in all places in the world where there is a developed dairy activity.

Producers use values between 50.000 and 100.000 per ml as a reference to indicate a regular amount of somatic cells in a cow. Thus, when this value is above what is considered normal (more than 250.000) it may mean that the animal is contaminated.

As we saw earlier, somatic cell values above this value (more than 250.000) can change the composition of the milk, directly affecting its quality. 

Somatic cell count (SCC) and diagnosis of bovine mastitis

Bovine mastitis is a very common inflammatory and infectious process that occurs in the animal's mammary gland. It brings great damage to the quality of the milk and a significant reduction in the animal's production capacity.

Cows that contract the infection become debilitated and, if not promptly treated, may even die. But the most serious case is subclinical mastitis, as in addition to not being detectable without the proper indicators, it helps to spread the disease through the herd.

Mastitis, or mastitis, as we also know it, is caused by microorganisms and their toxins, irritating chemical agents and physical trauma.

However, the most common cause that affects a significant part of the cattle herd are pathogenic microorganisms. They reach the animal through the breast canal.

Thus, the inflammation that occurs in the mammary gland is a reaction of the body trying to fight infectious microorganisms to try to resume the normal functions of the animal.

However, this process can cause other damage to the animal. Just to illustrate: the destruction of epithelial cells that are responsible for the synthesis of fundamental elements for milk quality, such as lactose and casein, even causing the milk to be discarded, which will be compromised in its composition and quality, due to the infection.