Milk (Exam 2)

Question 1

What are the different types of milk harvesting housing?

Answer 1

Tie stall barn: pipeline system above cow to carry milk from udder to bulk storage; stay in dry feed lots/barn; into holding pen; into milking parlor with doors open, walk in voluntary, door closes automatically
Parallel parlor: straight back
Herringbone parlor: angled
Rotary parlor
All these styles have pipelines below cows = good for milk as gravity pulls down and don’t ruin the quality of milk

Question 2

How is milking prepped?

Answer 2

Stimulation of milk let down and pre-stripping
Udder clipped/hair singed
Pre-dip
Single cloth towels
Backflush
Add Machine
Machine automatically released

Question 3

What occurs with stimulation of milk let down and pre-stripping?

Answer 3

Allow milk to squirt out to evaluate (45-60s)
Cows with mastitis are held out and not milked into the lane (puss in milk)

Question 4

Why/how are udders clipped/long hairs singed?

Answer 4

With cool flame
To prevent dirt and debris introduced in milk

Question 5

What is the purpose of pre-dip?

Answer 5

Stimulates teats and allows milk to come down (0.5% iodine)

Question 6

What is the purpose of single-cloth towels?

Answer 6

Removes pre-dip after 30 seconds of contact time
Teats clean and ready for machine application

Question 7

Define: Backflush and Machine Add On

Answer 7

2 vacuum system and massaging system
Pulsation mimicking calves
If suction too hard, start pulling blood and damages cap, ducts, and teat

Question 8

What is the purpose of the machine automatically releasing?

Answer 8

Measures milk let down and identifies when low milk volume

Question 9

What steps are taken to confirm that the cow is healthy and that the milk she produces is wholesome for consumption?

Answer 9

Each cow’s udder evaluated for heat, swelling, and pain to determine if milk is suitable for milking
Pre-stripping allows milk to squirt out before milking to evaluate the milk
Testing for mastitis of other infectious diseases that could lead to spoilage/bad/taste/dangerous milk

Question 10

What is the Pasteurized Milk Ordinance?

Answer 10

PMO
Make high quality product with low pathogens/bacteria
Govern design and maintenance of dairy farms and processing plants to make sanitation and milk quality uniform across state lines (adopted by most states

Question 11

What regulations are in the pasteurized milk ordinance?

Answer 11

Standard for milk harvest, storage, transport, cow facilities, equipment specification, cleaning processes
Inspections and oversights
Testing milk
Allowable limits for test results
Pasteurization standards
Packaging and handlin

Question 12

How does mastitis affect the cow, the milk, the quality of the milk, and the safety of the milk?

Answer 12

Inflammation of mammary gland = influx of inflammatory cells and mediators
Most commonly due to bacterial infection
Most common infectious disease of lactating cows
Cause disease in cow = cow health problem
NOT FOOD SAFETY PROBLEM
YES FOOD QUALITY PROBLEM = increase somatic cell count, milk composition changes
Abnormal milk/milk quality
Most common reason for antibiotic use in dairies (drug residue is major concern, withdrawal time after use)

Question 13

What are the clinical signs of mastitis in cows?

Answer 13

Local infections of udder = redness, swelling, heat, pain
Milk = clots, thick/thin, color
Systemic = fever, tachycardia, diarrhea, weakness, death

Question 14

What are the somatic cell tests?

Answer 14

California mastitis test: rapid; add milk to wells, add reagent, color change test = coagulates somatic/enucleated cells
Electronic SCC: test large numbers of individual cows (commercial dairies) monthly = look at summary (% up/down, compare parity/age, % herd with low SCC)

Question 15

What are the normal/high SCC values?

Answer 15

Normal: <250k
High Quality: <100k
Mastitis: >300K

Question 16

How is mastitis managed?

Answer 16

Bacterial culture: key to appropriate management of problem herds, determine why high SCC (sample from each teat and test)
Intramammary antibiotic infusion: routine treatment (inject locally, better tx than systemic)

Question 17

What are the bacterial sources of milk contamination?

Answer 17

Teat skin/canal (commensals)
Machine liners/tubers (improper procedures, cleaning, water temperature)
Mastitis
Systemic infections
Contaminants

Question 18

What are zoonotic pathogens in milk?

Answer 18

Pasteurization prevents disease spread!
Salmonella
E. coli
Campylobacter
MAP (feces)
Cryptosporidum

Question 19

What are bacterial pathogens that threaten animal health?

Answer 19

Mastitis

Question 20

What are bacterial pathogens that threaten milk spoilage?

Answer 20

Majority of bacteria in milk = spoilage bacteria
Psychotropic bacteria (spoilage)
Thermoduric bacteria (reduce shelf life) = micrococcus, microbacterium, lactobacillus, bacillus, clostridium

Question 21

How is milk moved on the farm and from the farm through the processing system?

Answer 21

Modern milking system = use pipelines to move milk faster, reduce exposure to air, chilled faster
Move to receiver tube to cooling tubes (plate coolers) to tank room/bulk tank
Agitator running to keep milk at right temp
Loaded onto trucks to be processes at milk plant

Question 22

What processes are used to assure highest milk quality?

Answer 22

Cooling/chilling to prevent microbial growth/spoilage (chilled and stored <40F)
Filtered to remove debris
Removed from farm to processing within 48 hours
Less exposure to air
Pipes moving downwards to not impact quality of milk
Pasteurization

Question 23

How have technological advances improved milk quality?

Answer 23

Automatic milking systems robotic milkers
Dairy tech pasteurizer

Question 24

Define: Dairy Tech Pasteurizer

Answer 24

Turbulent to take out clumps of pathogens and kill them off
More pipelines to increase movement of milk under certain temperatures to deliver to pasteurization
HTST method of pasteurization: milk in tank at low temperature (<40F) leaves from one tube to regenerator
Adjacent milk pipe is hot, leaving pasteurization and back to tank (low temp): hot milk warms up cold milk and vice versa
Additional heating phase added to bring milk >72F held for 15 seconds, then regenerated back to cooler temps
Energy efficient and neutralize pathogens

Question 25

What is the purpose of quality and safety testing of milk?

Answer 25

Every tanker or milk is tested
Single most tested food product, required by PMO
Evaluated for both safety and quality

Question 26

What tests are done for milk quality/safety?

Answer 26

Diagnostic milk culture
Somatic Cell: mastitis and milk quality
Residue testing: Beta lactams (abx)
Milking ring test: burcellosis

Question 27

What are the standard methods of quality testing of bulk milk?

Answer 27

Standard plate count
Preliminary incubation count
Lab pasteurized count
Coliform count
Sediment (dirt)
Freezing point (dilution)
Acidity, rancidity (bacterial/damage to milk)
Odor, color
Temp at pick up (<40F)

Question 28

Describe standard plate count (SPC)

Answer 28

Raw bacterial count of milk
Ideal <5k cfu/ml, may have problems at >10k cfu/ml, legal limit 100k
Strong relationship with ‘keeping’ quality of milk = leads to bacterial spoilage

Question 29

Describe preliminary incubation (PI) count

Answer 29

Incubate at 55F for 18hrs then plate for SPC
Measures: psychotrophic bacteria (in low temps, higher change of spoilage), raw milk keeping quality, sanitation practices on farms
Ideal <10k, acceptable <50k cfu/ml

Question 30

Describe lab pasteurized count (LPC)

Answer 30

Follow up to SPC
Incubate at 145F for 30min then place for SPC
Measures: thermoduric bacteria (reduce shelf life), equipment cleanliness, effective clean up (improper water temp, cleaner concentration, malfunctioning air injector), old rubber parts
Ideal <100-200, excellent equi hygiene <10

Question 31

Describe coliform count

Answer 31

Common fecal contaminants, test if water or milk has fecal contaminants (all bacteria, not just E. coli)
90F for 24hrs on selective media
Indication of sanitary production practices: cow, machine cleanliness, effective clean up
Ideal <10, acceptable <100cu

Question 32

Why are milk somatic cells measured and what do they tell us?

Answer 32

Help improve milk quality and alert you to early signs of mastitis
Helps quickly identify and treat infected animals and protect herd health and milk quality by preventing spread of bacteria
Somatic cells: nucleated cells, lining cells, inflammatory cells

Question 33

What is the role of pasteurization?

Answer 33

Process of heating every particle of milk in eqeuipment to specific past time/temp combination to reduce pathogens/bacterial load
Time/temp standards set for TB, brucella, coxiella, effective for other typical pahtogens
Standard commercial process does NOT sterilize, still have bacteria that leads to spoilage, enough removed to increase safety/shelf life

Question 34

What does pasteurization do to milk?

Answer 34

Prolongs shelf life (reduces spoilage bacteria)
Changes taste (not content of primary nutrients

Question 35

What is the time v temp relationship of pasteurization?

Answer 35

Higher temp = less time to reduce bacterial numbers in milk

Question 36

Define: long time holding pasteurization

Answer 36

140 degrees for 20 min
Neutral zone
Common

Question 37

Define: high temp, short time pasteurization

Answer 37

Heat milk to higher temp (161F) for short period (15s)
Common

Question 38

Define: ultrapasteurization

Answer 38

280F for 2sec
Organic milk

Question 39

Define: ultra high temp pasteurization

Answer 39

175-302F for 4-15sec
Rare (mexico because dont have good storage)
Sterilize product, can be left out for ~1yr before spoiling

Question 40

What zoonotic bacterial agents were the targets for setting pasteurization standards?

Answer 40

Coxiella burnetti
Brucella
TB

Question 41

Why do some people obtain unpasteurized milk?

Answer 41

Tastes different
Claims:
(1) human pathogens are rare on small raw milk farms
(2) helpful in combatting or curing numerous human diseases
(3) more nutrient dense than commercial pasteurized milk
(4) promoting as healthier than pasteurized

Question 42

How do some people obtain unpasteurized milk?

Answer 42

Small farms: retail sale vs cow shares
Own fraction of cow as investment, government cant say anything about what they do with it
Not allowed in PMO states (but approved for distribution in many states due to recent increased demand)

Question 43

What risks are being taken by consuming unpasteurized milk?

Answer 43

Not tested as intensely as commercial pasteurized milk
Could have antibiotic residues, high SCC, mastitis, pathogens = DANGEROUS
Many outbreaks traced to raw milk