Bulk tank milk ananalysis and herd management guide

Herd level information and bulk tank milk analysis: Tools for improving milk quality and herd udder health
(Sources: "Bovine Practitioner," Bhushan M. Jayarao et al., January 2001, 23-35)

Table 1. Benefits and Limitations of BTM analysis

Benefits

Limitations

1. Provides a logical approach for troubleshooting herds with multiple milk quality and mastitis related problems

2. Less expensive than quarter milk sampling the whole herd

3. BTM analysis can be done in about 96 hours

4. A reliable tool for veterinarians to troubleshoot milk quality and herd level mastitis

5. An important component of total herd health management or veterinary practice consultancy services

6. Bulk tank milk analysis report become documentary evidence of milk quality assurance protocol practiced on the farm.

1. Does not provide information about milk quality and mastitis at individual cow level

2. Understanding milk quality and mastitis problems in a herd cannot be done effectively using one single BTM sample

3. Information on herd management practices on milking cows, mastitis prevention, milk sanitation and general farm hygiene are required to interpret BTM analysis results.

4. Proper interpretation of BTM milk analysis results is critical before implementing changes on the farm

5. BTM samples cannot be frozen, they must be shipped on ice or icepacks.

6. BTM samples have to be processed within 36 hours of collection.

Table 2. How to conduct a bulk tank milk analysis

STEP ONE: Identify the issue			STEP TWO: Collection of bulk tank milk sample	STEP THREE: Laboratory tests
Issue	Q*	M+	When to collect ? At least 1-2 hours after milking, preferably should represent one milking. How to collect ? 1. Seek permission of owner 2. Agitate milk in the bulk tank for 10 minutes. 3. Wear disposable gloves. 4. Collect 2 ounces of milk from the top of the bulk tank using a clean sanitized dipper. 5. Transfer the milk to a 2 ounce whirlpack bag or 2 ounce snap cap vial. 6. Label the sample (farm, data, and note temp. on the bulk tank). How many samples to collect ? Establish a bulk tank milk profile: 4 samples (1 sample/week) How to transport the ample to laboratory ? Bulk tank milk sample must not be frozen, they should be shipped on ice or icepacks to the laboratory, such that the samples can be processed within 36 hours of collection. Information on farm management practices Use the standardized questionnaire to collect information on farm management practices.	What laboratory tests need to be done ?	Q*	M+
Low or no premium ?	v	v		Bulk tank milk somatic cell count	v	v
Persistent high bacterial counts ?	v	v		Standard plate count	v	v
Education of milkers	v	v		Preliminary incubation count	v
Bulk tank somatic cell count > 250,000 cells/ml ?	v	v		Coliform count	v	v
More mastitis cases in the last month ?		v		Styphylococcus aureus count		v
Buying the whole herd ?	v	v		Streptococcus agalactiae count		v
Monitor after herd expansion ?	v	v		Streptococci and Strep-like organisms		v
Suspect Mycoplasma in the herd ?		v		Coagulase negative staphylococci		v
Suspect Mycoplasma in the herd ?		v		Mycoplasma		v
Monitor fat and protein in milk ?	v			Mycoplasma		v
Monitor fat and protein in milk ?	v			Percent fat and percent protein		v

* Q means Milk quality + M means Mastitis

Table 3a. Interpretation of raw milk bacterial counts and suggested guidelines for trouble shooting high counts

Test and suggested counts

If counts are high for 3 out 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

2. Poor milking practices

3. Unclean or unsanitized milking equipment

4. Mastitis

1a. Temperature o milk 2 h after milking (must be <= 40⁰F)
1b. Check the bulk tank temperature indicator/thermometer for accuracy

2a. Evaluate udder preparation and milking procedures (See Table 7)

3a. Check for detergent and or sanitizer left in the containers
3b. Check water temp 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

4a. Check for history for Streptococcus agalactiae mastitis
4b. Check for cows with subclinical mastitis (perform Caliiformia 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

2. Faulty milking machine and worn out parts

3. Extremely dirty cows

1a. Persistent cleaning failure in some area of the milking system

1b. Same as SPC (3a-3e)

2a. Check for leaky pumps, old pipeline gaskets, inflations and other moisture traps

3a. Check for soiled udder and teats at time of milking. Determine if udders are flamed signed or clipped

Table 3b. Interpretation of raw milk bacterial counts and suggested guidelines for trouble shooting high counts

Test and suggested counts

If counts are high for 3 out 4 samples then the likely problem can be:

What to look for on the farm ?

Preliminary Incubation (PIC)

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

2. Managerial cooling of milk

3. Poor udder preparation before milking

1a. Same as SPC (3a-3e)

2a. Check temperature of milk in the bulk tank 2 hours after milking

3a. How are the cows cleaned and sanitized before milking ?
   1. Use of an approved pre-dip ?
   2. Teats dipped using a dip cup or spray ?
   3. Are cows fore-stripped ?
   4. Individual paper or cloth towels ?
   5. Teat and teat ends thoroughly clean and dry before attaching the milking unit ?
   6. 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

2. Herd history with regard to coliform mastitis

1a. Same as PIC (3a)
1b. Does the claw fall in 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

2a. Inquire if herd has had cases of clinical coliform mastitis ?
   If yes,
   1. What kind of bedding is used (sawdust, dried manure, washed sand) ?
   2. How is the bedding managed ?
   3. How frequently is it replaced ?
   4. Freestall area is wet all the time, 4-6 inches of manure in the allleys ? (Socks-like appearance on the feet of cows)

Table 4. Criteria that define excellent udder health status of individual cows and the herd.

Criteria	Ideal udder health targets
Bulk Milk Somatic Cell Count	< 250,000 cells/ml
Herd average ( actual)	< 200,000 SCC
Herd average ( DHI Linear Score)	< 3.0 LS SCC
100% of first calvers (DHI)	< 100,000 SCC
> 85% of herd	< 200,000 SCC
> 95% of herd	< 500,000 SCC
Incidence of Clinical Mastitis	< 25 cases /100 cows per year
Number of culls due to mastitis or other udder health problems	< 5 cases/ 100 cows a year

(source: Leslie, K.E. : Somatic cells counts: interpretation for individual cows.)

Table 5. Estimates of percent infected of quarters and losses in milk production due to elevated BTSCC

(Source: Harmon RJ: Somatic cell counts: myths vs reality. Proc 37th Natl Mastitis Council 40-50, 1998.)

Table 6a. Interpretation of results for contagious mastitis pathogens in bulk tank milk

Mastitis causing bacteria and suggested counts

If counts are high for 3 out of 4 samples then check for the following:

Suggested control measures

Staphylococcus aureus

Low
< 1 cfu/ml

Medium
< 100-500 cfu/ml

High
> 500 cfu/ml

1. Type of herd: closed herd, suggests the presence of chronic infection; open herd, suggests the likelihood of newly purchased animals as one of the possible source of Staph. aureus.

2. BTSCC in a herd with high Staph. aureus. infection generally ranges from 350,000 - 1000,000 cells/ml (most occasions 500,000 - 600,000 cells/ml)

3. Management practices that allow spread of Staph. aureus in the herd:
   1. Milking cows without gloves
   2. Cloth towels reused without proper cleaning
   3. Milking infected cows along with uninfected cows
   4. Poor fly control during summer
   5. During winter, milking cows with chappd teats
   6. Milking cows with teat and teat end injuries

1. CMT all newly purchased animals, and cows in milk with high SCC (>250,000 cells/ml)
2. Detect cows early with Staph. aureus mastitis by doing milk culture testing
3. Milk all infected cows last
4. Post milking test-dip cows
5. Dry-cow therapy
6. Use of individual paper towel or cloth towel
7. Back flush milking units using a sanitizing solution
8. Cull cows with chronic infection
9. Segregate herd if possible

Streptococcus agalactiae

Low
<1 cfu/ml

Medium
1000-5000 cfu/ml

High
> 6000 cfu/ml

1. Type of herd: closed herd, suggests presence of chronic infection; open herd, suggests both the likelihood of newly purchased animals bringing in the infection.
2. BTSCC in a herd with high Strep. agalactiae infection generally ranges from 500,000 - 600,000 cells/ml with high SPC ( 50,000 to > 100,000 cfu/ml)
3. Management practices that allow spread of Strep. agalactiae in the herd:
   1. Milking cows without gloves
   2. Cloth towels reused without proper cleaning
   3. Milking infected cows along with uninfected cows
   4. No or inadequate teat-dipping practices

1. CMT all newly purchased animals, and cows with high SCC (> 250,000 cells/ml)
2. Detect cowws early with Strep. agalactiae mastitis by milk culture
3. Teat-dip cows
4. Dry-cow therapy
5. Use of individual paper towels
6. Don't feed Strep. agalactiae containing milk to clves
7. Back flush milking units using a sanitizing solution
8. Milk all infected cows last

Table 6b. Interpretation of results for contagious mastitis pathogens in bulk tank milk

Mastitis causing bacteria and suggested counts

If counts are high for 3 out of 4 samples then check for the following:

Suggested control measures

Mycoplasma

1. Type of herd: closed herd, suggests the presence of chronic infections in the herd that would include animals of all ages; open herd, suggests the likelihood of newly purchased animals as one of the possible source of Mycoplasma, which is the most frequent cause of a Mycoplasma outbreak in a herd that has expanded recently.
2. BTSCC is generally > 500,000 cells/ml when there are more than 5 to 10% of the cows with Mycoplasma infection.

3. Management practices: poor herd health management practices with a history of Mycoplasma pnuemonia in the herd including calves; hygroma in adult cattle; cows treated for clinical mastitis do not respond to treatment; cloth towels and cannulas are reused without proper cleaning and disinfection; and the herd has expanded recently

1. Perform whole herd culture
2. Segregate infected and non-infected cows
3. Attention needs to be given to newly purchased animals.
4. Improve milking hygiene
5. Cow to cow transfer of infection can occur while milking, therefore, cows with Mycoplasma IMI should be milked last
6. Milkers should wear rubber gloves
7. Use individual paper towels
8. Cull cows that are infected with Mycoplasma
9. Monitor bulk tank milk monthly for Mycoplasma.

Corynebacterium bovis

Low
<500 cfu/ml

Medium
500-1000 cfu/ml

High
> 1000 cfu/ml

* C. bovis is infrequently found in bulk tank milk, is highly contagious, but less of a pathogen

1. Type of herd: little information is available as to the type of herd and the occurrence of C. bovis mastitis. It can be presumed to be similar to other contagious bacteria.
2. BTSCC do not generally increase, but when there are many cows with C. bovis subclinical mastitis the BTSCC may be aaround 350,000 - 500,000 cells/ml.
3. Management practices: when teat-dipping and dry-cow therapy are not practiced or improperly implemented, C. bovis is frequently isolated. Teat-end lesions can cause C. bovis to colonize and allow there spread in the herd.

1. All cows should be pre0dipped before milking
2. Evaluate teat-dipping practices
3. All cows to be dried off, should be dry-cow treated
4. Treat cows for teat end lesions

Table 6c. Interpretation of results for contagious mastitis pathogens in bulk tank milk

Bacteria and their counts

If counts are high ( > 1000 bacteria/ml) for 3 out of 4 samples then the following corrective actions can be done

Most frequently observed problems

Corrective actions

1. Streptococci and Strep-like organisms (SSLO)

2. Coagulase negative Staphylococci (CNS)

3. Coliforms (E. coli, Klebsiella, Enterobacter, Citrobacter)

4. Non-coliforms (Pseudomonas, Serratia, Proteus, Acientobacter, Moraxella, Hafnia)

SSLO, CNS, Non-coliforms

Low < 500 cfu/ml

Medium 500-1000 cfu/ml

High > 500 cfu/ml

Coliforms

Low < 10 cfu/ml

Medium 10-50 cfu/ml

High > 50 cfu/ml

* See table 6d for list of bacterial species isolated from bulk tank milk.

BTSCC
1. Streptococci and Strep-like organisms: 250,000- 450,000 cells/ml.
2. CNS: 350,000 - 500,000 cells/ml
3. Coliforms: < 300,000 cells/ml
4. Non-coliforms: No data
Milking Procedures
5. No established milking protocol
6. Milking procedures not consistent (varies from milker to milker and shift to shift)
7. Poor udder surface (clipping or flaming not done)
8. Teat and teat ends not thoroughly cleaned
9. Milking done on wet teats
10. Cloth towels reused without cleaning
Farm Hygiene
1. Poor bedding management
2. Manure removal not done regularly

Milking procedures ( See table 7 for recommended milking procedures)
1. Pre-dipping and post-dipping practices on the farm (Use of approved teat dip, teat-dip concentration, application method, and application time of pre-dip need to be evaluated)
2. Cleaning teat and teat ends before milking
a. Individual paper towels recommended, if cloth towels are used, clean and sanitized towels should be used only once during the milking operation
b. Teat and teat ends must be thoroughly cleaned, and must be dry before applying the milking unit. Wet and unclean teat and teat ends increase the risk of mastitis in the herd.

Udder health
1. Perform California Mastitis Test on a regular basis for cows in early ( by 6th milking) and late lactation (0- 3 days before drying off)
2. Dry treat all cows before drying off
3. Frequently examine teat and teat end condition. Cows with bruised teats and teat end injuries are more likely to get infected with mastitis causing bacteria.

Milking machine
Milking machine needs to be inspected periodically by a professional. Attention needs to be given to liner slips and vacuum levels. Excessive liner slips and faulty vacuum levels can pre-dispose cows to mastitis.

Bedding in tie or free stalls
Wet and dirty bedding harbor the environmental bacteria and between milkings can get inside the teat canal, or on the surface of teat and teat ends. Advocate dry and clean bedding that is worked on at least twice a day.

Table 6d. Bacterial species isolated from bulk tank milk.

Group of bacteria

Species ( species indicated in bold associated with subclinical and clinical mastitis)

Coagulase-negative Staphylococci

Streptococci and Strep-like organisms

Coliforms

Gram-negative non-coliform bacteria

S. caprae, S. chromogenes, S. cohnii, S. epidermidis, S. hominis, S. hyicus, S. intermedius, S. lentus, S. simulans, S. warneri, S. xylosus

S. mutans, S. salivarius S. alactolyticus, S. bovis, S. equinus, S. uberis, E. faecalis, E. faecium. E. saachrolyticus, E. avium, E. durans, E. hirae. E. malodoratus. S. agalactiae, S, dysgalactiae, S. equi, S. equisimilis, S. zooepidemicus, S. downei, S. acidominimus, S. thermophilus.

Escherichia coli, Citrobacter fruendii, Klebsiella spp, Enterobacter spp.

Acinetobacter, Hafnia, Moraxella, Pseudomonas, Serratia

Stanchion / Tie stall		Parlor
Step	Operation	Step	Operation
1	Wear Gloves	1	Wear Gloves
2	Wipe off excess dry manure, straw and bedding	2	Wipe off excess dry manure, straw and bedding
3	Strip each teat into a stripcup	3	Strip each teat into a stripcup
4	Dip teats with an approved pre-dip. Allow the pre-dip to react for at least 30 sec.	4	Dip teats 3-4 cows with an approved pre-dip. Allow the pre-dip to react for at least 30 sec.
5	Clean teat and teat ends using single paper towel or individual cloth towel	5	Return to the first cow and clean teat and teat ends using a single paper towel or individual cloth towel
6	The teats must be dried for at least 15 sec	6	The teats must be dried for at least 15 sec
7	Attach milking machines immediately after teats are dried	7	Attach milking machines immediately after teats are dried
8	Dip teats with post-dip immediately after milking	8	Dip teats with post-dip immediately after milking