What Is Somatic Cell Count?
If you sell milk commercially or aspire to, you'll quickly become familiar with Somatic Cell Count — or SCC. It's one of the most important indicators of milk quality and udder health, and it directly affects your payment rate in most dairy supply agreements.
Somatic cells are white blood cells and shed epithelial cells naturally present in milk. When a cow's udder is healthy, these numbers stay low. When infection or inflammation occurs — as with mastitis — the immune system floods the udder with white blood cells, and SCC rises sharply.
How Is SCC Measured?
SCC is expressed as the number of cells per millilitre of milk (cells/mL). Bulk tank SCC represents the average across your entire herd and is what processors and co-ops typically monitor. Individual cow SCC tests give you insight into which animals are driving the problem.
Most dairy processors conduct regular bulk tank sampling. On-farm California Mastitis Test (CMT) kits offer a quick, inexpensive way to screen individual cows at milking time.
What Do the Numbers Mean?
| SCC (cells/mL) | Interpretation |
|---|---|
| Below 100,000 | Excellent — very low infection pressure |
| 100,000 – 200,000 | Good — acceptable for commercial milk |
| 200,000 – 400,000 | Moderate — investigate individual cows |
| Above 400,000 | High — mastitis likely; action required |
EU regulations typically require bulk tank SCC to remain below 400,000 cells/mL for commercial milk production. Many processors apply bonus/penalty payment schemes that reward farmers maintaining consistently low counts.
Why High SCC Hurts Your Milk
Beyond regulatory thresholds, high SCC has real practical consequences:
- Reduced yield: Udder inflammation damages milk-secreting cells, reducing output from affected quarters.
- Lower quality: High-SCC milk has altered protein and fat composition, affecting cheese yield and flavour.
- Shorter shelf life: Enzymes released by somatic cells break down milk fat and protein more quickly.
- Financial penalty: Most price structures penalise milk above threshold SCC levels.
Common Causes of Elevated SCC
- Subclinical or clinical mastitis (the most common cause)
- Poor milking hygiene and teat preparation
- Worn or incorrectly calibrated milking equipment
- Overmilking or inadequate milking intervals
- Stress, nutritional deficiencies, or high-yielding cows at peak lactation
How to Reduce SCC in Your Herd
- Identify affected cows: Use CMT or individual milk recording to find which animals are contributing most to bulk tank SCC.
- Review milking procedure: Consistent teat preparation, correct cluster attachment, and prompt removal after milking all make a difference.
- Check equipment: Have your milking machine serviced annually; liner condition is especially important.
- Dry cow therapy: Work with your vet to implement an appropriate dry-off treatment protocol to clear infections between lactations.
- Improve housing and hygiene: Clean, dry bedding dramatically reduces environmental mastitis pathogens.
The Bottom Line
SCC is a mirror of your herd's udder health. Monitoring it closely — and acting quickly when it rises — protects both your cows' wellbeing and your bottom line. Think of it not as a compliance number, but as one of the most useful management tools available to you.