Somatic cell count measures the number of cells present in milk and serves as a vital indicator of udder health in cows. Elevated levels signal infection, often leading to reduced milk yield and financial losses for dairy operations. High SCC causes changes in milk composition and shortens shelf life, which affects both product quality and processor acceptance. Studies show that every 100,000-cell increase can reduce milk production by 5.5 pounds per cow per day. The table below displays recent SCC averages:
| Region | Average SCCS | WTSCC | Percentage SCCS (0-3) | Percentage SCCS (7-9) |
|---|---|---|---|---|
| Indiana | 2.86 | 276,000 | 65% | 6% |
| Florida | 3.44 | N/A | N/A | N/A |
Key Takeaways
- Somatic cell count (SCC) is crucial for assessing udder health in cows. Lower SCC indicates healthier cows and better milk quality.
- High SCC can lead to significant economic losses for dairy farmers. Every 100,000-cell increase can reduce milk production by 5.5 pounds per cow per day.
- Regular monitoring of SCC helps detect infections early. Farmers should test SCC at least once a month to maintain herd health.
- Effective management practices, such as proper milking techniques and hygiene, can help lower SCC and improve milk quality.
- Understanding SCC levels allows farmers to make informed decisions about treatment and milk sales, ultimately protecting their profits.
What Is Somatic Cell Count?
Somatic cell count measures the number of somatic cells present in milk. Scientists use this measurement to assess milk quality and udder health in dairy cows. Somatic cell count is expressed in cells per milliliter. Healthy cows typically show less than 100,000 cells/mL, while cows with infections often exceed 250,000 cells/mL. A lower somatic cell count suggests better food safety and higher milk quality. Farmers and veterinarians rely on this marker to detect harmful bacteria in the herd.
Cell Types in Milk
Milk contains several types of somatic cells. The most common are white blood cells, which include neutrophils, macrophages, and lymphocytes. Each type plays a unique role in the cow’s immune system.
- Neutrophils act as the first line of defense against pathogens. Their numbers rise sharply during infection.
- Macrophages help signal other white blood cells to respond to threats.
- Lymphocytes remain present in both healthy and infected cows, but their proportion drops as somatic cell count increases.
The overall increase in somatic cell count during infection reflects the cow’s immune response in the mammary gland.
SCC and Infection
Somatic cell count rises when cows experience infections such as mastitis. Infected mammary quarters show a mean somatic cell count of 210,520 cells/mL, much higher than the 32,720 cells/mL found in healthy quarters. The highest somatic cell count often appears with specific pathogens like Enterobacter species, reaching up to 338,000 cells/mL. Farmers use somatic cell count to identify subclinical mastitis, which often results from bacterial intramammary infection. Elevated somatic cell count signals a strong immune reaction and helps pinpoint cows needing attention.
Why SCC Matters?
Milk Quality
Somatic cell count plays a critical role in determining milk quality. High somatic cell count often signals mastitis in cows, which leads to changes in milk composition. These changes include reduced fat content and increased chloride ion concentration. Both factors lower milk quality and make the product less desirable for consumers. The presence of more somatic cells also means more bacteria in the milk. Bacteria can produce enzymes that survive heat treatment and cause off-flavors, especially as milk sits on the shelf. This reduces milk quality and shortens shelf life. The table below highlights how somatic cell count affects milk quality, taste, and shelf life:
| Evidence Type | Description |
|---|---|
| Correlation between SCC and milk quality | High somatic cell counts indicate the presence of mastitis, which negatively affects milk composition, leading to reduced fat content and increased chloride ion concentration. |
| Impact on taste | Bacterial contamination from high SCC can produce heat-stable enzymes that lead to off-flavors in milk, especially during shelf life. |
| Shelf life implications | Milk with high SCC is more prone to spoilage due to increased bacterial load, affecting safety and quality. |
Milk quality remains a top priority for dairy producers. Monitoring somatic cell count helps maintain high milk quality and ensures that processors accept the product.
Economic Impact
Somatic cell count directly affects the financial health of dairy operations. High somatic cell count leads to lower milk quality, which results in milk being rejected or sold at a lower price. Dairy farmers experience significant economic losses when somatic cell count rises. The table below shows the financial losses linked to high somatic cell count:
| Factor | Financial Loss (USD) |
|---|---|
| Average economic loss over 3 months | 557 |
| Gains from treating affected cow over 3 years | 1,158.7 |
| SCC Level | Daily Loss (USD) |
|---|---|
| ≥100,000 cells/mL (Month 1) | 1.20 |
| ≥100,000 cells/mL (Month 10) | 2.06 |
High somatic cell count not only reduces milk quality but also lowers milk yield and increases costs.
Key impacts include:
- Lower milk production per cow.
- Reduced pregnancy rates.
- Increased death losses.
- A difference of 11 pounds in milk production per cow per day results in $159 in net farm income.
Dairy producers who control somatic cell count protect milk quality and improve their bottom line. Regular monitoring and prompt action help maintain milk quality and reduce financial risk.
Cow Health
Mastitis Indicator
Mastitis stands as one of the most common diseases in dairy herds. It causes inflammation in the mammary gland, usually from bacterial sources. This disease leads to significant economic losses for dairy producers. Somatic cell count serves as a reliable indicator of intramammary infection. When the count rises, the risk of mastitis increases. Monitoring somatic cell count helps identify cows with early or subclinical mastitis before visible symptoms appear. Researchers found that somatic cell count score predicts mastitis incidence more accurately than other measures. Including this score in herd health analysis allows for better detection and management of mastitis cases. Early intervention reduces the spread of infection and protects milk quality.
Herd Health Effects
High somatic cell count affects more than just individual cows. It impacts the entire herd’s health and productivity. The following table shows the increased risk of culling for different breeds when somatic cell count remains high:
| Breed | Risk of Culling (times greater) |
|---|---|
| Holstein | 4.95 |
| Ayrshire | 6.73 |
| Jersey | 6.62 |
Elevated somatic cell count links to several negative outcomes:
- Reduced reproductive performance and increased days open.
- Higher death loss rates, not only from mastitis but also from overall poor health.
- Lower net farm income and increased replacement costs.
- Serves as an index of animal husbandry skills.
Lowering somatic cell count benefits dairy farms by increasing profits and improving herd longevity. Every 100,000-cell increase in bulk tank somatic cell count results in a loss of 5.5 pounds of milk per cow per day. The main reason to reduce somatic cell count is to prevent milk losses caused by mastitis and maintain herd health.
SCC Standards
Legal Limits
Every country sets its own legal limit for somatic cell count in milk. These limits help protect public health and ensure product quality. The United States allows a higher somatic cell count than many other countries. For example, the legal limit in the United States is 750,000 cells per milliliter. Costa Rica sets a lower limit at 400,000 cells per milliliter. The table below compares legal limits and measurement methods:
| Country | Legal Limit (somatic cells/mL) | Method of Measurement |
|---|---|---|
| United States | 750,000 | Count of 37 somatic cells from 20 fields at 1000X |
| Costa Rica | 400,000 | Count of 20 somatic cells from a milk sample at 1000X |
Legal limits focus on protecting consumers and maintaining basic standards for milk safety.
Industry Guidelines
Industry guidelines often set stricter targets than legal requirements. Many leading dairy organizations recommend lower somatic cell counts to improve milk quality and meet consumer expectations. The table below shows recommended limits in several countries:
| Country | SCC limit (cells mL−1) |
|---|---|
| European Union | 400,000 |
| New Zealand | 400,000 |
| Switzerland | 350,000 |
| Australia | 400,000 |
| Canada | 400,000 |
| United States of America | 750,000 |
- Industry guidelines often set stricter SCC limits than legal standards.
- Legal limits focus on milk quality and safety, while industry guidelines aim for lower counts for better quality.
- The trend is moving towards lower SCC limits, especially in the US, driven by consumer and scientific pressure.
Producers who follow industry guidelines can achieve higher quality milk and gain a better reputation in the market. Lower somatic cell counts also support animal health and long-term dairy success.
Measuring SCC
Lab Tests
Laboratories use advanced technology to measure somatic cell count in milk. The most accurate methods include direct detection techniques. These involve fluorescence photoelectric counting, Coulter counting, and flow cytometry. The DCC, a reference method, measures from 10,000 to 4,000,000 cells per milliliter. It shows a coefficient of variation of 12% at 100,000 cells/mL, 8% at 400,000 cells/mL, and 7% at 1,000,000 cells/mL. Flow cytometry stands out for its precision and reliability. Somatic cell count tester can process up to 600 samples per hour. Laboratories also use improved image analysis and new reference materials to enhance accuracy. These methods help dairy producers monitor milk quality and herd health.
| Detection Method | Type | Example Equipment |
|---|---|---|
| Fluorescence Counting | Direct | Flow Cytometer |
| Coulter Counting | Direct | DCC |
| Image Analysis | Direct | Somacount FCM |
| ATP Bioluminescence | Indirect | Portable SCC Analyzer |
| CMT | Indirect | CMT Paddle |
On-Farm Methods
Farmers often use the california mastitis test to check for subclinical mastitis. The cmt uses a detergent reagent that reacts with cellular contents in milk, causing increased viscosity. Farmers add the reagent to a milk sample, agitate it, and score the reaction. The cmt is simple, cost-effective, and sensitive to changes in somatic cell count. It helps identify infected quarters and supports treatment decisions. However, the cmt does not provide exact numbers and can lead to errors if used alone. Operator interpretation may vary, and the cmt cannot replace direct laboratory tests. Some farms use portable somatic cell count test kit. These innovations allow instant detection and support herd management.
- The cmt detects subclinical mastitis quickly.
- The cmt is best used with other tests for accurate results.
- The cmt is not as precise as laboratory methods.
Interpreting SCC Results
High vs. Low Counts
Somatic cell count (SCC) results help dairy farmers and veterinarians understand udder health and milk quality. High SCC often points to infection, while low SCC suggests healthy cows. The following table shows how to interpret different SCC levels:
| SCC Level (cells/mL) | Interpretation |
|---|---|
| 100,000 or less | Indicates an ‘uninfected’ cow |
| 200,000 | Threshold for determining infection with mastitis |
| >200,000 | Highly likely to be infected in at least one quarter |
| >300,000 | Likely to be infected with significant pathogens |
| >400,000 | Deemed unfit for human consumption by the EU |
A cow with an SCC below 100,000 cells/mL usually has a healthy udder. When SCC rises above 200,000 cells/mL, the risk of mastitis increases. Milk with SCC over 400,000 cells/mL does not meet European Union standards for human consumption. Farmers use these thresholds to make decisions about treatment and milk sales.
What Numbers Mean?
SCC numbers provide important clues about herd health and milk quality.
- A threshold of 200,000 cells/mL often defines intramammary infection (IMI).
- Monthly individual SCC tests give a clear picture of udder health in the herd.
- High SCC signals subclinical mastitis and lower milk quality.
- Low SCC links to better udder health and higher milk quality.
- Differential somatic cell count (DSCC) helps assess inflammation and its effect on milk composition.
- Bulk-tank SCC (BTSCC) of 200,000 cells/mL or more shows ongoing or recent infection in the herd.
- Higher BTSCC means more severe infections.
Regular SCC monitoring allows early detection of problems and supports better herd management. Farmers who understand these numbers can protect both milk quality and cow health.
Causes of High SCC
Risk Factors
Many factors contribute to elevated SCC levels in dairy cows. Researchers have identified several key risk factors that increase the likelihood of high somatic cell counts. The following table summarizes the most common risk factors:
| Risk Factor | Description |
|---|---|
| Cow Parity | Older cows tend to show higher SCC than first-lactation cows. |
| Body Condition Score | Both very low and very high scores raise the risk of high SCC. |
| Seasonality | SCC often peaks during summer and autumn. |
| Previous SCC Levels | Past test-day SCC predicts current SCC levels. |
| Days in Milk (DIM) | SCC drops between 41–100 DIM, then rises after 100 days. |
| Herd Size | Large herds maintain more stable SCC than small family-owned herds. |
Dairy specialists also note these additional risk factors:
- Previous test-day SCC
- Cow parity
- Month of lactation
- Very low or high body condition score
- Mild and moderate udder contamination (which may decrease risk)
Farmers who monitor these factors can identify cows at risk and take steps to prevent problems.
Management Issues
Management practices play a major role in controlling somatic cell count. Poor milking technique, lack of hygiene, and inadequate treatment of mastitis can all lead to higher SCC. The table below highlights how specific practices affect SCC:
| Management Practice | SCC Category |
|---|---|
| Dry cow treatment | High |
| Milking technique | High |
| Postmilking teat disinfection | High |
| Antibiotic treatment of clinical mastitis | High |
| Attention to hygiene | Low |
| Mineral supplementation | Low |
Effective management strategies include:
- Regular cleaning of milking lines
- Performing strip cup tests
- Using the California mastitis test
- Washing teats with water before milking
Additional tips for reducing SCC:
Provide a low-stress environment for cows.
Wipe off teats with a clean towel, using a different towel for each cow.
Pre-dip and post-dip teats to disinfect before and after milking.
Forestrip each quarter prior to milking.
Consistent attention to these details helps maintain low SCC and supports herd health.
Reducing SCC
Prevention Tips
Dairy farms can lower somatic cell count by following proven prevention strategies. Monthly milk quality tests help identify cows with high cell counts. Farms should milk these cows last to reduce the spread of infection. Clean milking practices play a vital role in keeping bacteria away from the udder. Understanding which bacteria cause mastitis allows for targeted treatment. Farms that develop a treatment plan based on the identified bacteria see better results. Tracking average somatic cell count helps monitor progress and adjust strategies.
Effective prevention steps include:
- Identify high-SCC cows through regular milk testing.
- Milk high-SCC cows last and maintain strict hygiene during milking.
- Determine the bacteria responsible for mastitis in the herd.
- Create a treatment plan tailored to the bacteria found.
- Track SCC averages to measure improvement.
Tip: Farms that focus on prevention see fewer cases of mastitis and higher milk quality.
Monitoring Practices
Routine monitoring supports healthy cows and high-quality milk. Monthly milk quality tests reveal herd trends and help spot infected animals early. Bulk tank cultures show which bacteria are present in the milk supply. Monitoring somatic cell count gives insight into udder health and helps manage both contagious and environmental infections. Regular SCC tests detect subclinical mastitis before symptoms appear. Early treatment prevents infection from spreading and protects milk production.
Key monitoring practices:
- Monthly milk quality tests for herd assessment.
- Bulk tank cultures to identify bacteria types.
- Routine SCC tests to catch subclinical mastitis.
- Early intervention to maintain milk yield and cow health.
Farms that combine prevention and monitoring achieve lower somatic cell count and better overall dairy performance.
Somatic Cell Count Myths
Common Misconceptions
Many people misunderstand what somatic cell count means for dairy products. Some believe that milk contains pus if the somatic cell count is high. This idea is incorrect. Somatic cells are immune cells, not pus. Their presence in milk is a natural response to inflammation, especially during mastitis. These cells help protect the cow from infection. Regulatory agencies, such as the FDA and the European Union, set strict limits on somatic cell counts to ensure milk safety. The following list highlights common misconceptions:
- Some claim that high somatic cell count means milk is unsafe, but regulatory standards keep it within safe limits.
- Many think somatic cells are harmful, but they are part of the cow’s immune defense.
- The belief that milk contains pus comes from misunderstanding the role of somatic cells.
Note: Somatic cells are normal and expected, especially when cows fight infection.
Testing Myths
Testing for somatic cell count also brings confusion. Some dairy producers trust only on-farm tests, while others doubt the accuracy of laboratory methods. Each method has strengths and weaknesses. Indirect detection methods, such as the California mastitis test, do not provide exact counts. These tests lack sensitivity and specificity, so results may not always reflect the true somatic cell count. Bacterial contamination can also affect test signals, leading to errors. For example, the California mastitis test only shows if mastitis is present, not which bacteria cause it.
Direct detection methods, like Coulter counting, offer more precise results but require expensive equipment and trained staff. These methods sometimes cannot separate somatic cells from bacterial cells, which may cause interference. Many believe that all tests are equally reliable, but this is not true. Understanding the limits of each method helps dairy farmers make better decisions about herd health.
Conclusion
Monitoring somatic cell count remains essential for maintaining high-quality milk and healthy dairy herds. Farms that keep SCC low benefit from higher yields, better product quality, and improved profitability. The table below highlights long-term advantages for producers:
| Benefit | Description |
|---|---|
| Higher Milk Purchase Price | Low SCC milk earns premium prices and access to better markets. |
| Increased Cow Productivity | Cows with low SCC produce more milk and have longer productive lives. |
| Lower Treatment Costs | Early detection reduces expenses for mastitis and antibiotics. |
Dairy producers should apply best practices and stay informed about new technologies and industry standards to ensure ongoing success.
FAQ
What Is Considered a Normal Somatic Cell Count in Milk?
A normal somatic cell count in milk usually falls below 100,000 cells per milliliter. This level indicates healthy udders and high milk quality. Most dairy processors prefer milk with low somatic cell counts for better taste and longer shelf life.
How Often Should Dairy Farmers Test for Somatic Cell Count?
Dairy farmers should test somatic cell count at least once a month. Regular testing helps identify problems early. Early detection allows for quick treatment and prevents the spread of infection within the herd.
Can High Somatic Cell Count Affect Milk Taste?
Yes, high somatic cell count can change milk taste. Bacteria and enzymes from infected udders may cause off-flavors. Consumers often notice a difference in freshness and quality.
Does Somatic Cell Count Only Indicate Mastitis?
Somatic cell count mainly signals mastitis, but other factors can raise it. Stress, injury, or late lactation may also increase cell counts. Farmers should investigate all possible causes when levels rise.
Are There Penalties for Exceeding Legal Somatic Cell Count Limits?
Yes, milk that exceeds legal somatic cell count limits may face rejection or price penalties.
Processors and regulators enforce these limits to protect public health and ensure product quality.