Somatic Cell Count Reduction: A Step-by-Step Herd Protocol

When bulk tank somatic cell count (SCC) creeps up, the temptation is to treat and cull your way out. University of Minnesota Extension is blunt about that: lowering SCC through treatment and culling alone is often futile, and the real answer is to find the root cause of the infections. This protocol follows that logic. It is a framework to work through with your veterinarian and milk quality team, not a prescription for any individual cow. For background on what the numbers mean, see our guide to somatic cell count and milk quality.

Step 1: Build the team and set the target

Extension suggests forming a milk quality team that includes your veterinarian, key employees, your plant field representative and extension staff. Agree on measures you will track: bulk tank SCC, clinical mastitis rate and new infection rate. The Minnesota guide gives two useful benchmarks: fewer than 5 clinical cases per 100 milking cows per month is a good goal (1 to 2 is excellent), and a new infection rate under 8 percent per month. Ohio State's guidance classes bulk tank SCC under 200,000 cells per milliliter as low risk, 200,000 to 400,000 as medium, and over 400,000 as high.

Step 2: Define the problem

Pull your DHI records and clinical case logs and ask who is affected. Are infections new or chronic? Heifers or older cows? Fresh cows or mid-lactation? A particular pen? A pattern tells you where to look. The Minnesota extension article recommends culturing the 10 to 30 most recent clinical cases (sampled before any treatment) and some cows with SCC over 200,000 for two or more months. It adds that several bulk tank cultures are needed before contagious organisms can be ruled out.

Step 3: Sort contagious from environmental

This sorting decides everything else.

• Contagious organisms (Strep. agalactiae, Staph. aureus, Mycoplasma) spread at milking. Controls include segregating positives and milking them last, gloves, minimizing liner slips, correct equipment function and post-milking teat dip. Strep. ag usually responds well to treatment, while Staph. aureus and Mycoplasma do not.
• Environmental organisms (coliforms, Strep-like organisms, Staph species) come from bedding, mud and manure. Controls focus on clean, dry lying areas, clean dry teats at prep, teat dip, dry cow housing and teat sealants at dry-off.

Step 4: Tighten the milking routine

Ohio State's key-points list is a good checklist. Strip 4 to 5 squirts per quarter, use a strip cup, pre-dip with an approved germicide left on for 30 seconds, dry with a single-use towel and wait 60 to 90 seconds after prep before attaching the unit. Dip after every milking and discard dip contaminated with manure. See our article on a consistent milking routine for how to train it into a crew.

Step 5: Check the machine

Maintain correct vacuum to protect teat ends, and keep the milking system, the cooling tank and all milk-handling connections clean. Make sure water heating meets cleaning requirements. Have the system tested on a schedule by a qualified technician.

Step 6: Fix the dry period and fresh pen

Minnesota notes that about half of infections occur during the dry period. Ohio State's guidance reports that more than 95 percent of new dry-period infections occur in quarters with open teat canals, and that cows still giving over 36 pounds a day in the final week before dry-off were more than 7 times as likely to be infected at calving as cows giving 24 pounds or less. Cutting yield before dry-off helps canals close. Use intramammary antibiotics or teat sealants as your veterinarian directs, following the label. Link this work to transition cow management.

Step 7: Clean up the environment

Keep bedding dry and clean, give transition cows one stall each and at least 30 inches of bunk space, and fix leaks and clogged flush lines so water does not pool in alleys. Our cow comfort guide goes deeper.

Step 8: Handle cows deliberately

Milk known infected cows last or separate them. Culture before treating clinical cases, because antibiotics mainly help susceptible pathogens, and let your vet decide on treatment and duration. Ohio State notes that mild to moderate cases often resolve in a few days regardless, while severe cases need hydration and pain relief. Cull chronic cows when they continue to infect others. Keep treatment records, doses and withdrawal times.

Step 9: Keep the herd as closed as practical

Before buying animals, review their SCC and mastitis history and test for contagious pathogens where possible. Our mastitis guide adds more on prevention.

Step 10: Review monthly

The Minnesota guide advises monthly adjustments. If progress stalls, either the plan is not being carried out properly or the problem was misidentified. Assign each action to a named person with a deadline, because plans fail on follow-through more often than on science.

Where to start

Begin with the highest-impact, lowest-cost items: prep routine, post-dip, bedding, and a culture to confirm the organisms. Then work toward larger investments. The Ohio State Buckeye Dairy News article is worth printing for the parlor wall. For market context see farm.fm's dairy section, and for extension and lab contacts try the Agriculture Directory. Your veterinarian should own diagnosis and treatment decisions. This site is independent and not affiliated with any breed association.