Farm Hygiene on Dairy Farms: 10 Steps to Lower SCC

Good farm hygiene on a dairy comes down to four control points: clean milker hands, clean cows, clean equipment and fast milk cooling. Get them right and the bulk-tank somatic cell count (SCC) stays low. The US national average for herds on Dairy Herd Improvement (DHI) testing was 181,000 cells/mL in 2024, according to Progressive Dairy’s report on the CDCB summary, while the federal Grade “A” limit is 750,000 cells/mL.

This guide sets out ten dairy hygiene steps in the order milk moves: from the milker, to the cow, to the parlor, the tank, the barn and the records. It also shows the SCC limits that apply in the US and Canada, how herd size relates to high-SCC tests, and a calculator that tests whether a mastitis-prevention spend pays back on your own herd.

Why farm hygiene shows up on the milk check

Somatic cells are mostly white blood cells. A healthy udder always has some. When bacteria get into the teat and cause mastitis, the count rises. That is why buyers and regulators use SCC as the main test of milk hygiene and udder health.

The federal rules for US Grade “A” milk are in the Pasteurized Milk Ordinance (PMO). The 2019 revision of the PMO sets three limits for each producer’s raw milk: SCC no higher than 750,000 cells/mL, a bacterial count no higher than 100,000 per mL before it is mixed with other farms’ milk, and no positive drug residue test. Repeated failures lead to warning letters and, in the end, a suspended permit.

Some states set tighter limits. Progressive Dairy’s summary lists 600,000 in California, 500,000 in Oregon and 400,000 in Idaho and Washington. It also notes that 400,000 is the current maximum for milk used in dairy products for export.

Money matters too. In four of the 11 Federal Milk Marketing Orders (Central, Mideast, Southwest and Upper Midwest), the producer price is adjusted for every 1,000 cells above or below a 350,000 base, and the size of that adjustment changes each month with the wholesale cheese price, per the same Progressive Dairy summary. Many processors also pay their own quality premiums. Ask your buyer for the schedule in your contract.

The larger loss is usually milk you never ship. The California Dairy Quality Assurance Program (CDQAP) says a cow’s daily yield falls about 1 to 2 pounds for every doubling of her SCC above 50,000, and that bulk-tank counts of 500,000 and 1,000,000 have been linked with production losses of 6% and 18%.

Dairy SCC limits in the US and Canada

The legal ceiling depends on where you ship. The US federal limit is the highest of those shown here. Canada’s dairy sector agreed on a national standard of 400,000 cells/mL in 2012, and every province changed its rules to match, says Dairy Farmers of Canada. Canada also limits bacteria: under 122,000 individual bacteria cells per mL by Bactoscan, or 50,000 CFU/mL by plate loop count.

Chart

Raw milk SCC limits in selected places

thousand cells/mL, legal or industry maximum

Whatever the limit, a farm with good dairy farm hygiene aims well below it. A herd that sits near the limit can fail one test after a bad week, a heat wave or a few new cases of mastitis.

How dairy hygiene has improved over time

US herds have cut their average SCC a long way. The Council on Dairy Cattle Breeding (CDCB) reports national DHI averages back to 1995. The CDCB research report on DHI somatic cell counts shows the high point was 322,000 in 2001. By 2021 the average was 179,000 cells/mL. CDCB links the fall to better management, including directed culling and genetic selection.

Chart

US average test-day SCC in DHI herds

thousand cells/mL, selected years

The 2024 summary covered 8,250 herds and about 3.7 million cows. In 2024, 29 states lowered their average SCC and 14 of them improved by 10,000 or more. Arkansas, Oklahoma and Tennessee still averaged above 300,000. North Dakota and Michigan led the 20 states at or below the national average.

Season matters as well. In the CDCB data, SCC rose from April to August and then fell through January. Heat and humidity raise bacterial load in bedding, so summer is when hygiene slips show up first.

Does herd size change the risk?

In the 2021 CDCB data, small herds had more test days with high counts. If the limit were 400,000, 14.5% of monthly tests in herds under 50 cows would have been over it, against 0.2% in herds with more than 4,000 cows. Average SCC fell as herd size grew up to about 1,000 cows.

Chart

Monthly tests above 400,000 cells/mL by herd size

share of DHI herd test days, 2021, selected herd sizes (cows)

That does not mean small herds cannot have clean milk. It means a small herd has less room for error: one cow with a high count is a bigger share of the tank. The steps below work at any size; only the equipment changes.

The 10 farm hygiene steps at a glance

1. Milker hygiene: the first line of farm hygiene

Milkers’ hands carry contagious mastitis bacteria such as Staphylococcus aureus from one cow to the next. Bare skin has small cracks where bacteria hide. Mississippi State University Extension advises milkers to wear gloves, change them when dirty or disinfect them during milking, because the smooth surface is easier to keep clean than hands.

• Wash hands and forearms before milking starts.
• Wear nitrile gloves and a clean apron or sleeves each shift.
• Rinse or dip gloved hands when they get soiled, and between groups of cows.
• Keep food, drink and smoking out of the parlor.
• Train new staff on the routine before they milk alone, and check it from time to time.

Best for: every herd. Gloves and a written routine cost little and are easy to check.

2. Clean, dry cows

A cow that arrives at the parlor with manure on her udder and legs carries environmental bacteria straight to the teat end. Prep can remove some of it, but not all. Keeping cows clean is cheaper than cleaning dirty cows at milking.

• Keep stalls and resting areas dry and clean so cows lie down on clean bedding.
• Clip or trim tails and udder hair where your herd’s practice allows, so manure does not stick and spread.
• Score cow hygiene (legs, udder, flank) once a month and track the share of dirty cows.
• Look at the cause when scores worsen: bedding, crowding, alleys or wet weather.

Avoid washing whole udders where you can: wet udders drip dirty water into the teat cup. If you must wash, use as little water as you can and dry each teat fully.

3. The milking routine: pre-dip, forestrip, dry, post-dip

A steady routine is the core of milking hygiene. The Mississippi State guide sets out four steps:

1. Pre-dip. Cover each teat with an effective pre-dip, such as an iodine product. Leave it on for the contact time on the label; the extension guide gives 30 to 45 seconds.
2. Forestrip. Strip two or three squirts from each quarter. Look for flakes or clots, a sign of clinical mastitis. Stripping also helps milk let-down.
3. Dry. Wipe each teat with a clean cloth or paper towel, one per cow, using a downward motion. Launder cloths in a bleach detergent between milkings.
4. Post-dip. Dip teats as soon as the unit comes off. The teat opening stays open for about an hour after milking, so this step protects it while it closes.

Pre-dip mainly targets environmental bacteria. Post-dip mainly targets contagious bacteria. Use teat dips as the label directs, and ask your veterinarian which product suits the bacteria found on your farm.

4. Clean milking equipment after every milking

Milk left in lines, claws and liners feeds bacteria and builds films that the next wash cannot reach. The University of Wisconsin Milk Research and Instruction Lab teaches the standard cycle: rinse, detergent wash, acid rinse, then sanitize before the next milking.

• Rinse with lukewarm water right after milking to flush out milk.
• Wash with a hot alkaline detergent. A University of Idaho Extension guide says the wash should start at 140 to 160°F and should ideally still be 120 to 130°F at the end, unless the detergent maker allows lower. It notes that each 18°F drop halves the chemical’s activity.
• Acid rinse to remove mineral deposits and lower the pH. Never mix acid and alkaline cleaners.
• Sanitize just before the next milking.

Replace liners and rubber parts on the schedule the maker gives, and sooner if they crack or lose shape. For a full step-by-step wash routine, see our guide to dairy farm cleaning procedures.

5. Cool milk fast and keep it cold

Cooling is the step that protects all the work before it. Bacteria in warm milk multiply quickly. The PMO requires Grade “A” raw milk to be cooled to 50°F (10°C) or less within four hours of the start of the first milking, and to 45°F (7°C) or less within two hours after milking ends. The blend temperature after later milkings must not go above 50°F (10°C).

• Check that the tank reaches temperature on time, after every milking.
• Use a recording thermometer or data logger and keep the charts.
• Keep the milk room clean and closed, apart from the wash area where possible.
• Service the cooling unit before summer, when heat loads peak.

A high bacteria count with a normal SCC often points to a cooling or washing fault rather than sick cows. Check the wash and the tank first.

6. Barn, bedding and airflow

Most environmental mastitis starts where cows lie down. Wet, dirty bedding holds bacteria such as E. coli and Streptococcus uberis close to the teats for hours each day.

• Top up or replace bedding on a fixed schedule; remove wet and soiled patches daily.
• Keep stall beds level and dry, with good drainage.
• Run fans and open sides to cut heat and humidity, which raise bacterial growth in summer.
• Avoid overcrowding: more cows than stalls means more cows lying in alleys.
• Keep fresh cows and dry cows on clean bedding too.

Best for: herds whose SCC climbs each summer, which matches the April-to-August rise in the national data.

7. Manure handling and dairy farm sanitation

Manure is the main source of environmental bacteria on a dairy. How often you scrape and where you store it shape both cow hygiene and water safety.

• Scrape or flush alleys at least as often as cows go to milking, and more in wet weather.
• Keep holding pens and exit lanes clean so cows do not walk back to their stalls with dirty feet.
• Store manure and compost on hard surfaces with runoff controls, away from wells and streams.
• Spread manure by a nutrient plan; US states and Canadian provinces set rules on timing and rates.

Footbath waste goes into manure too. Copper in used footbath solution builds up in soil when the manure is spread on fields, which is one reason to use no more copper than you need (see step 8). Check local rules on manure storage and spreading before you change your system.

▶ Seven plain-English ways to protect soil and water on the farm. · 4:34

8. Hoof care and footbaths

Lame cows lie down more, often in dirtier places, and digital dermatitis spreads through wet, dirty alleys. Hoof care is part of hygiene, not only a vet job.

The University of Kentucky’s dairy program advises a footbath at least 8 feet long (10 feet preferred), with at least 5 inches of solution so the hoof is covered up to the dewclaws. It says copper sulfate solution should be changed after 150 to 300 cow passes because manure binds the copper.

Strength and frequency both matter. Ohio State University’s Buckeye Dairy News summarised a Journal of Dairy Science study: with weekly use, a 2% copper sulfate bath worked nearly as well as a 5% bath. When baths ran only every other week, the 2% solution fell well short.

Trim hooves on a regular schedule with a trained trimmer, and watch how cows walk as they leave the parlor. Follow the product label and local rules for footbath chemicals and their disposal; formalin, for example, needs eye, skin and breathing protection.

Chart

Digital dermatitis before and after 8 weeks of footbaths

% of cows with an active lesion, by copper sulfate strength and frequency

9. Sick cows, isolation and biosecurity

Fast action on a sick cow stops one case from becoming a herd problem. It also keeps drug residues out of the tank.

• Mark treated cows clearly and milk them last or into a separate unit.
• Withhold milk for the full withdrawal time on the label or your vet’s instructions.
• Keep a hospital pen apart from the main herd, with its own clean bedding.
• Run bulk-tank cultures from time to time to spot contagious bacteria such as Staph. aureus or Mycoplasma early, as CDQAP recommends.
• Test and quarantine bought-in cattle before they join the herd.
• Control rodents, birds and flies, and limit visitor and vehicle traffic near the cows.

Work with your veterinarian on treatment choices. CDQAP notes that no systemic antibiotics are approved for treating mastitis in the US, so any injectable use for mastitis is extra-label, needs vet oversight and carries longer withdrawal times.

10. Records and SCC tracking

Records turn good habits into a system you can check. Without them, a slow rise in SCC goes unseen until a buyer’s test fails.

• Log every bulk-tank result (SCC and bacteria) and plot it monthly.
• If you test on DHI, look at individual cow SCC to find the few cows driving the tank count.
• Record every clinical case: date, quarter, treatment and outcome.
• Keep wash and cooling records next to the milk results so you can link a spike to a cause.
• Review the numbers with staff and your vet each month.

CDCB publishes state and national DHI averages each year. Compare your herd with your state, not only the national figure, because climate shifts the baseline.

▶ Six simple steps to start using farm data and satellite maps. · 4:18

Troubleshooting a high SCC or bacteria count

When a test comes back high, the pattern of the numbers points to the likely cause. Use this table as a starting point, then confirm with your milk quality advisor or veterinarian.

Two points help here. First, the bulk tank is an average: a handful of cows with very high counts can lift the whole tank. If you test individual cows, sort them by SCC and look at the top few first. Second, bacteria counts react within a day or two to a wash or cooling fault, while SCC reflects infections that may have built up over weeks. So a fast change in bacteria with a steady SCC points first to the milk room rather than the cows.

When the cause is not clear, a bulk-tank culture tells you which kinds of bacteria are present. Contagious types such as Staph. aureus call for tighter parlor hygiene and segregation. Environmental types such as coliforms and Strep. uberis call for work on bedding, alleys and cow cleanliness. CDQAP describes routine bulk-tank culture as one of the most useful tools for watching udder health.

A simple hygiene checklist by frequency

Most of the steps above become routine once they sit on a schedule. A written checklist also makes it easier to train new staff and to show an inspector what you do.

Every milking

• Milkers in clean gloves and clothes.
• Pre-dip, forestrip, dry with one towel per cow, attach, post-dip.
• Treated cows milked last or into a marked unit; their milk kept out of the tank.
• Equipment rinsed, washed, acid rinsed and drained.
• Tank temperature checked after cooling.

Every day

• Soiled bedding removed and stalls levelled.
• Alleys and holding pen scraped or flushed.
• Lame, sick or off-feed cows noted and checked.
• Wash and cooling records reviewed for faults.

Every week

• Footbath run on the planned schedule and changed by cow passes.
• Bedding topped up or replaced.
• Liners and hoses inspected for cracks.
• Teat end and teat skin checked on a sample of cows.

Every month

• Bulk-tank SCC and bacteria results plotted and compared with the month before.
• Cow hygiene and lameness scored on a sample of the herd.
• Clinical mastitis cases counted and the rate worked out per 100 cows.
• Records reviewed with staff and, where possible, your veterinarian.

Every year

• Milking system tested by a qualified technician.
• Cooling unit serviced before summer.
• Written milking and cleaning routines updated and staff retrained.
• Your herd’s average compared with your state’s DHI average.

What does mastitis cost, and does prevention pay?

Mastitis is the most common and most costly disease of adult dairy cows, says CDQAP. It puts the usual loss per clinical case at $100 to $200, and up to $400 to $600 in some cases. The Mississippi State guide gives an average of about $326 per case for first-lactation cows and $427 for older cows, from a 2017 estimate.

CDQAP also quotes a common rule of thumb of $3 to $5 saved for every $1 spent on prevention, while noting that the return varies from farm to farm. The calculator below lets you test that on your own herd: enter your case rate, your cost per case and what a new prevention step would cost.

Try the numbers for your own farm below.

How satellite maps fit into farm hygiene

Hygiene happens in the barn and parlor, so satellites cannot see it. They can help with the land around a dairy. Field maps show where forage is growing well, where pasture is short and where wet areas stay wet after rain, which matters for grazing herds and for planning when and where to spread manure. Farmonaut shows satellite vegetation maps for the fields you draw, on web, Android or iOS.

Related pages on our site: large farm management · mobile apps · carbon footprinting · product traceability · crop loan and insurance · fleet management · developer API docs

▶ How satellite NDVI maps show stress across a large farm before it is visible on the ground. · 4:09

FAQ

What is farm hygiene on a dairy?

It is the set of daily habits that keep bacteria out of milk and away from the udder: milker hygiene, clean cows, a fixed milking routine, equipment washing, fast cooling, clean bedding, manure handling, hoof care, sick-cow control and records. Bulk-tank SCC and bacteria counts are the usual measures.

What SCC is legal for Grade “A” milk in the US?

The PMO limit is 750,000 cells/mL for each producer’s raw milk. Some states set lower limits: 600,000 in California, 500,000 in Oregon and 400,000 in Idaho and Washington, per Progressive Dairy. Milk for export is held to 400,000.

What is a good bulk-tank SCC?

The US DHI average was 181,000 cells/mL in 2024. CDQAP says herds with a bulk-tank SCC under 200,000 do not usually see large losses from subclinical mastitis. Many quality premiums reward counts lower still; check your buyer’s schedule.

How fast must milk be cooled?

Under the PMO, to 50°F (10°C) or less within four hours of the start of the first milking, and to 45°F (7°C) or less within two hours after milking ends.

Should I use both pre-dip and post-dip?

Mississippi State Extension recommends both: pre-dip to cut environmental bacteria before the unit goes on, and post-dip to protect the open teat end after milking. Follow the product label for contact time.

How often should a copper sulfate footbath be changed?

The University of Kentucky’s dairy program says after 150 to 300 cow passes, because manure binds the copper. Follow the label and local rules for disposal.