Bulk Tank Monitoring Guidelines

Interpretation of raw milk bacterial counts and suggested guidelines for troubleshooting high counts

Test and suggested counts If counts are high for 3 out of 4 samples then the likely problem can be What to look for on the farm?

Standard Plate Count (SPC)

Low (Good)
< 5,000 cfu/ml

Medium (Acceptable)
< 10,000 cfu/ml

High (Concern)
> 10,000 cfu/ml

1. Improper cooling of milk 1a. Temperature of milk 2 hr after milking, (must be ≤ 40°F)
1b. Check the bulk tank temperature indicator/thermometer for its accuracy
1c. Ask if any recent changes have been masde to cooling system
2. Poor milking practices 2a. Evaluate udder preparation and milking procedures (see Table 7).
3. Unclean or unsanitized milking equipment 3a. Check for detergent and or sanitizer left in the containers
3b. Check water temperature used for cleaning
3c. Enquire about water quality (chlorination, well water management, coliform count, pH, water hardness)
3d. Ask if equipment is sanitized between milkings
3e. If pails and buckets are used, ask how they are cleaned
4. Mastitis 4a. Check for history of Streptococcus agalatiae mastitis
4b. Check for cows with subclinical mastitis (perform California mastitis test

Lab. Pasteurization Count (LPC)

Low (Good)
< 100 cfu/ml

Medium (Acceptable)
100 – 200 cfu/ml

High (Concern)
> 200 cfu/ml

1. Unclean milking equipment and utensils. 1a. Persistent cleaning failure in some area of the milking system
1b. Same as SPC (3a – 3e)
2. Faulty milking machine and worn out parts. 2a. Check for leaky pumps, old pipeline gaskets, inflations and other rubber parts and milk stone deposits
2b. Check air lines and moisture traps
3. Extremely dirty cows. 3a. Check for soiled udder and teats at time of milking. Determine if udders are inflamed, singed or clipped.

Interpretation of raw milk bacterial counts and suggested guidelines for troubleshooting high counts

Test and suggested counts If counts are high for 3 out of 4 samples then the likely problem can be What to look for on the farm?

Preliminary Incubation Count (PI)

Low (Good)
< 10,000 cfu/ml

Medium (Acceptable)
10,000 – 50,000 cfu/ml
OR < 3x to 4x SPC

High (Concern)
50,000 cfu/ml
OR>3x to 4x SPC

1. Unclean milking equipment and utensils 1a. Same as SPC (3a – 3e)
2. Marginal cooling of milk 2a. Check temperature of milk in the bulk tank 2 hours after milking
3. Poor udder preparation before milking 3a. How are the cows cleaned and sanitized before milking?
  • Use of an approved pre-dip?
  • Teats dipped using a dip cup or spray?
  • Are cows fore-stripped?
  • Individual paper or cloth towels?
  • Teat and teat ends thoroughly clean and dry before attaching the milking unit
  • Use of an approved post-dip?

Coliform Counts (CC)

Low (Good)
< 10 cfu/ml

Medium (Acceptable)
10 – 50 cfu/ml

High (Concern)
> 50 cfu/ml

1. Poor udder preparation before milking 1a. Same as PI (3a)
1b. Does the claw fall in the manure during milking
1c. Look for wet udders during milking
1d. Look for worn rubber hoses and gaskets
1e. Check milk filter after milking for fecal matter.
2. Herd history with regard to coliform mastitis 2a. Enquire if herd has had many cases of clinical coliform mastitis? If yes,
  • What kind of bedding is used (sawdust, dried manure, washed sand)?
  • How is the bedding managed?
  • How frequently is it replaced?
  • Freestall area is wet all the time, 4-6 inches of manure in the alleys? (Socks like appearance on the feet of the cows)

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