Many producers misread somatic cell count results due to sampling errors, misunderstanding of thresholds, or improper use of equipment. Accurate interpretation of somatic cell count plays a vital role in protecting milk quality and herd health. They often overlook the need for a reliable somatic cell count tester and correct sampling techniques. Producers should review their interpretation of somatic cell count and consider if mistakes impact their operation.
Key Takeaways
Always match somatic cell count thresholds to your region and testing method to avoid misinterpretation.
Collect milk samples from the right source—quarter, cow, or bulk tank—to get accurate information about mastitis.
Consider non-infectious factors like cow age, lactation stage, stress, and hygiene before diagnosing mastitis based on somatic cell count.
Use proper sampling techniques and regularly calibrate your somatic cell count tester to ensure reliable results.
Combine somatic cell count data with other tests and maintain good milking hygiene to protect herd health and milk quality.
SCC Thresholds
Understanding Thresholds
Somatic cell count (SCC) thresholds help producers evaluate milk quality and detect mastitis. Different regions set varying limits for SCC in dairy cows. These thresholds reflect the risk of subclinical mastitis and milk quality standards. Producers often rely on these values to decide when to take action against mastitis or improve herd management.
Dairy Species
SCC Threshold (cells/mL)
Region/Country
Basis for Threshold Determination / Notes
Dairy Cows
≤ 200,000
Sweden
Acceptability breakpoint; milk quality and subclinical mastitis diagnosis
Dairy Cows
≤ 400,000
Slovakia, EU countries, Australia, New Zealand, Canada
Standard for class 1 milk quality
Dairy Cows
≤ 500,000
Brazil, India
Milk quality standard
Dairy Cows
≤ 750,000
USA
Milk quality standard
Dairy Cows
> 200,000
Lithuania (experiment)
Optimal SCC threshold for California Mastitis Test (CMT) to identify intramammary infection (IMI); sensitivity 79%, specificity 95%
Statistical analysis and diagnostic tests, such as the California Mastitis Test and flow cytometry, help determine these thresholds. Higher SCC levels often indicate subclinical mastitis, which can reduce milk yield by about 2.5% for every 100,000 cells/mL above 200,000. Producers should understand that SCC thresholds vary by country and testing method.
Common Misinterpretations
Many producers misinterpret SCC results by assuming a single threshold applies everywhere. They may overlook regional differences or the impact of testing methods. Some believe that SCC above the threshold always means clinical mastitis, but subclinical mastitis often causes elevated SCC without visible symptoms. Others ignore the possibility of false positives due to factors like stress or recent calving.
Tip: Producers should match SCC thresholds to their region and testing method. They should not rely solely on SCC to diagnose mastitis. Regular monitoring and understanding the difference between clinical mastitis and subclinical mastitis improve the interpretation of somatic cell count.
Producers who understand SCC thresholds and avoid common misinterpretations protect herd health and maintain milk quality.
Sample Source Matters
Quarter, Cow, or Bulk Tank
The source of the milk sample plays a crucial role in interpreting somatic cell count results. Producers often collect samples from individual quarters, entire cows, or the bulk tank. Each source provides different information about mastitis and milk quality.
Quarter samples help identify which part of the udder shows signs of mastitis or subclinical mastitis.
Cow-level samples give an overview of the animal’s health and can reveal subclinical mastitis that affects more than one quarter.
Bulk tank samples reflect the overall somatic cell count for the herd but may hide cases of subclinical mastitis in individual cows.
Note: Sampling from the wrong source can lead to misdiagnosis. Producers may miss subclinical mastitis in a single quarter if they only test bulk tank milk.
Impact on Interpretation
The interpretation of somatic cell count changes depending on the sample source. Quarter samples allow producers to pinpoint mastitis and subclinical mastitis in specific areas. Cow-level samples help detect subclinical mastitis that does not show visible symptoms. Bulk tank samples provide herd-level data but can mask individual cases of mastitis or subclinical mastitis. Producers sometimes assume that a low bulk tank somatic cell count means the herd is free from mastitis. This mistake can allow subclinical mastitis to persist undetected. A high somatic cell count may indicate widespread subclinical mastitis or even clinical mastitis in the herd. Producers should compare results from different sources to get a complete picture of mastitis risk.
Best Practices:
Use quarter samples to detect early subclinical mastitis.
Monitor cow-level somatic cell count to track individual health.
Analyze bulk tank somatic cell count for herd management.
Investigate high somatic cell count results to find hidden mastitis cases.
Tip: Producers who understand the impact of sample source improve mastitis control and protect milk quality.
Non-Infectious Factors
Parity and Production
Parity and milk production influence somatic cell count results. Cows in early lactation often show higher somatic cell counts. Heifers may have lower counts compared to older cows. Producers sometimes misinterpret elevated somatic cell count as mastitis when it actually reflects normal changes during lactation. Older cows tend to experience more episodes of mastitis and subclinical mastitis. Their immune systems respond differently during each lactation. High-producing cows may show increased somatic cell count due to stress on the udder, not just mastitis. A table below summarizes how parity and production affect somatic cell count and the risk of mastitis or subclinical mastitis:
Parity/Lactation Stage
SCC Trend
Mastitis Risk
Subclinical Mastitis Risk
Heifers (1st lactation)
Lower
Lower
Lower
Older cows
Higher
Higher
Higher
Early lactation
Variable
Moderate
Moderate
Peak production
Higher
Higher
Higher
Note: Producers should consider parity and lactation stage before diagnosing mastitis or subclinical mastitis based on somatic cell count alone.
Stress and Hygiene
Stress and poor hygiene can elevate somatic cell count without infection. Cows under heat stress or nutritional stress often show increased somatic cell count. This rise does not always mean mastitis or subclinical mastitis. Dirty bedding and improper milking routines expose cows to bacteria. These conditions increase the risk of mastitis and subclinical mastitis. Producers sometimes mistake stress-related somatic cell count changes for mastitis. A checklist helps producers reduce non-infectious causes of elevated somatic cell count:
Provide clean bedding and stalls.
Maintain consistent milking routines.
Monitor cow comfort during lactation.
Reduce heat and nutritional stress.
Tip: Producers who address stress and hygiene improve herd health and lower the risk of mastitis and subclinical mastitis during lactation.
Sampling Errors
Technique Issues
Proper sampling technique plays a critical role in obtaining accurate somatic cell count score. Many producers make mistakes during milk collection, which can lead to misinterpretation of mastitis risk. For example, failing to strip foremilk before sampling can result in a higher somatic cell count. Foremilk often contains more cells, especially if the cow has mastitis in one quarter. Using too much milk or adding an incorrect amount of reagent can also affect the test outcome. These errors may cause a false elevation or reduction in the somatic cell count, leading to unnecessary mastitis treatments or missed cases.
Producers should always follow best practices for sample collection. They should use clean equipment and collect milk after discarding the first streams. Consistent technique helps ensure that the somatic cell count reflects the true health status of the udder. Accurate sampling allows for better mastitis control and supports herd health.
Tip: Training all staff on proper sampling methods reduces the risk of errors and improves mastitis detection.
Tester Accuracy
The accuracy of the somatic cell count tester directly impacts the reliability of results. A poorly calibrated device can give misleading readings, which may result in incorrect mastitis diagnosis. Producers sometimes overlook the need to check and calibrate their somatic cell count tester regularly. This oversight can cause them to miss early signs of mastitis or to treat cows unnecessarily.
Manufacturers provide guidelines for calibrating each somatic cell count tester. Producers should follow these instructions and keep records of calibration dates. Using a reliable and well-maintained tester ensures that the somatic cell count accurately reflects the presence or absence of mastitis. Regular calibration supports effective mastitis management and helps maintain milk quality.
Note: Always verify the calibration of the somatic cell count test kit before starting a new round of mastitis screening.
Infection vs. Other Causes
Immune Response
Dairy cows show a distinct immune response when infection triggers an increase in somatic cell count. The body recruits immune cells to the udder, especially during mastitis. Neutrophils dominate in cases of clinical mastitis, while M1 macrophages play a larger role in mild or subclinical mastitis. The somatic cell count rises as neutrophils flood the milk, signaling an acute inflammatory reaction. Producers often see a sharp increase in cytokines such as TNFα and IL-8 within the first day of infection. Later, other cytokines like IL-1α, IL-1β, and IL-6 peak, reflecting ongoing immune activity.
The following table summarizes the immune response pattern in dairy cows with elevated somatic cell count due to infection:
Aspect
Description
Immune cells recruited
Mainly neutrophils and M1 macrophages; neutrophils dominate in clinical mastitis, M1 macrophages in mild/subclinical mastitis
Somatic Cell Count (SCC)
Elevated SCC reflects neutrophil influx; higher SCC in clinical mastitis compared to mild/subclinical mastitis
Cytokine secretion pattern
Early sharp increase in TNFα and IL-8 at 24 hours; peaks of IL-1α, IL-1β, IL-6, and adaptive immunity cytokines occur later
Gene expression changes
Early upregulation of immune pathways; sustained immune gene expression in mild/subclinical mastitis, transient in clinical mastitis
Clinical mastitis bacterial load peaks early and declines; mild/subclinical mastitis load increases slowly and persists
This pattern shows that somatic cell count increases mainly because of neutrophil recruitment during mastitis. The severity and duration of mastitis depend on the type of infection and the cow’s immune response.
Non-Infectious Elevations
Not all increases in somatic cell count result from mastitis or subclinical mastitis. Several non-infectious factors can raise somatic cell count and complicate interpretation. Producers should consider these influences before diagnosing mastitis or subclinical mastitis.
Parity affects somatic cell count. Cows with more lactations often show higher somatic cell count due to accumulated udder tissue damage.
Season plays a role. Pasture season can significantly change somatic cell count levels.
Stage of lactation influences somatic cell count. Early or late lactation periods may show different patterns.
Milk yield impacts somatic cell count. High-producing cows sometimes have elevated somatic cell count unrelated to mastitis.
Studies reveal that non-infectious factors explain a larger portion of somatic cell count variation than infectious causes. In goats, parity and season strongly affect somatic cell count even without intramammary infections. Producers must account for these factors when interpreting somatic cell count to avoid misdiagnosing mastitis or subclinical mastitis.
Tip: Producers who recognize non-infectious causes of elevated somatic cell count improve udder health management and reduce unnecessary mastitis treatments.
Bulk Tank SCC and Milk Quality
Herd-Level Monitoring
Bulk tank somatic cell count offers a valuable tool for monitoring herd health. Dairy producers use this measurement to assess overall milk quality and detect trends in mastitis. A rising somatic cell count in the bulk tank often signals an increase in subclinical mastitis within the herd. Producers track these numbers over time to spot patterns. They can identify periods when mastitis cases spike or when subclinical mastitis becomes more common. This approach helps producers take action before milk quality drops.
Bulk tank testing does not pinpoint individual cows with mastitis. Instead, it provides a snapshot of the entire herd. Producers often combine bulk tank results with individual cow testing. This strategy improves detection of subclinical mastitis and supports better mastitis control. Consistent monitoring helps maintain high milk quality and reduces the risk of undetected mastitis spreading.
Tip: Producers should record bulk tank somatic cell count results regularly. This habit helps them respond quickly to changes in mastitis levels.
Common Pitfalls
Many producers make mistakes when interpreting bulk tank somatic cell count. They may assume a low count means no mastitis exists in the herd. In reality, a few cows with severe subclinical mastitis can raise the count, while many cows with mild mastitis may go unnoticed if their cases balance out. Producers sometimes overlook the impact of subclinical mastitis on milk quality. Even small increases in somatic cell count can signal hidden mastitis problems.
Another common error involves ignoring seasonal changes. Hot weather or poor hygiene can cause spikes in mastitis and subclinical mastitis. Producers who do not adjust their management may see a decline in milk quality. They should also avoid relying only on bulk tank results. Individual cow testing remains essential for finding cows with subclinical mastitis or early mastitis.
Common pitfalls to avoid:
Ignoring small increases in somatic cell count.
Failing to investigate the source of high counts.
Overlooking the role of subclinical mastitis in milk quality loss.
Relying solely on bulk tank data for mastitis control.
Note: Effective mastitis management requires both herd-level and individual monitoring. This approach protects milk quality and reduces the impact of subclinical mastitis.
Species Differences and Goat Milk Quality
SCC in Goats
Goat milk presents unique challenges when interpreting somatic cell count. Unlike cow milk, goat milk naturally contains a higher somatic cell count, often ranging from 1,100,000 to 1,300,000 cells per milliliter. This elevated level results from the apocrine secretion process in goats, which releases more epithelial cells and cell fragments into the milk. In cows, a high somatic cell count usually signals mastitis or inflammation. In goats, however, a high somatic cell count does not always indicate mastitis. Many healthy goats show elevated counts, especially during late lactation or after stressful events.
Producers sometimes misinterpret these results. They may treat goats for mastitis based solely on somatic cell count, even when no infection exists. This mistake can lead to unnecessary treatments and increased costs. Understanding the natural variation in goat milk helps prevent these errors.
Note: Always consider the species-specific differences before diagnosing mastitis based on somatic cell count alone.
Factors Affecting Goat Milk Quality
Several factors influence goat milk quality and the interpretation of somatic cell count. Mastitis remains a primary concern, but other elements also play a role. Parity, stage of lactation, and environmental stress can all raise the somatic cell count in goats. Older goats and those in late lactation often show higher counts, even without mastitis. Poor hygiene and improper milking routines increase the risk of mastitis and can further elevate the somatic cell count.
A table below summarizes key factors affecting goat milk quality and somatic cell count:
Factor
Effect on SCC
Mastitis Risk
Parity
Higher in older goats
Increased
Stage of lactation
Higher in late stage
Increased
Hygiene
Poor hygiene raises SCC
Increased
Stress
Raises SCC
May increase
Producers who monitor these factors can better manage mastitis and improve goat milk quality. They should avoid relying solely on mastitis somatic cell count. Instead, they should combine SCC results with clinical signs and regular herd health checks.
Interpretation of Somatic Cell Count: Best Practices
Practical Tips
Accurate interpretation of somatic cell count helps producers manage mastitis and maintain milk quality. Producers should use automated cell counters, such as DeLaval or Fossomatic, to reduce subjectivity and improve efficiency. These devices provide reliable results and support early detection of mastitis. Understanding physiological changes is important. Somatic cell count often rises in early lactation, so producers must consider the stage of lactation during interpretation of somatic cell count. Regulatory standards, like EU Regulation EC No 853:2004 and ISO 13366-1, set clear limits for somatic cell count in milk. Producers should follow these standards to ensure compliance and protect herd health.
Milking hygiene and equipment performance play a key role in mastitis prevention. Clean teats and well-maintained machines reduce the risk of infection and false elevations in somatic cell count. Producers should train staff to collect samples correctly and operate testing equipment. Proper training leads to more accurate interpretation of somatic cell count and better mastitis control.
Tip: Combine somatic cell count results with other tests, such as the California Mastitis Test, to confirm mastitis and avoid unnecessary treatments.
Checklist
A reliable interpretation of somatic cell count depends on a systematic approach. Producers can use this checklist to improve mastitis detection and milk quality:
Use automated, rapid cell counters for consistent results.
Recognize normal somatic cell count variations during different lactation stages.
Monitor teat condition and milking routines to prevent mastitis.
Train personnel in sample collection and equipment use.
Support somatic cell count findings with complementary mastitis tests.
This checklist helps producers identify mastitis early and ensures accurate interpretation of somatic cell count. Consistent use of these steps protects herd health and supports high-quality milk production.
Conclusion
Producers often misinterpret somatic cell count results, which leads to poor decisions and reduced milk quality. Common mistakes include ignoring sample source, overlooking non-infectious factors, and using uncalibrated testers. These errors can harm herd health and lower milk quality.
Accurate interpretation of somatic cell count supports better mastitis control.
Producers should follow best practices and consult professionals to protect herd health and improve milk quality.
FAQ
What Doesa High Somatic Cell Count Indicate?
A high somatic cell count usually signals inflammation in the udder. This often means mastitis, but stress, stage of lactation, or poor hygiene can also cause elevated counts. Producers should investigate the cause before starting treatment.
How Often Should Producers Test Somatic Cell Count?
Producers should test somatic cell count at least once a month. More frequent testing helps detect mastitis early. Regular monitoring supports better herd health and milk quality.
Can Somatic Cell Count Vary Between Species?
Yes, somatic cell count varies between species. Goat milk naturally has higher counts than cow milk. Producers must use species-specific thresholds to avoid misdiagnosis and unnecessary treatments.
Does Bulk Tank Somatic Cell Count Reflect Individual Cow Health?
Bulk tank somatic cell count shows the overall herd status. It does not identify which cows have mastitis. Producers need individual cow testing to find and treat affected animals.
Why Is Proper Sampling Important for Accurate Results?
Proper sampling prevents contamination and ensures reliable results. Incorrect technique can give false readings, leading to missed mastitis cases or unnecessary treatments. Training staff in correct sampling methods improves accuracy.
