Milk Hygiene

Question 1

1. Percentage water in milk?
2. Percentage butter fat in milk?
3. Percentage protein in milk?
4. Percentage lactose and other carbohydrates in milk?
5. Trace products in milk?

Answer 1

1. 87%
2. 4%
3. 3.2%
4. 4.8%
5. Salt, minerals, vitamins, wbc, bacteria, enzymes, gland cells.

Question 2

1. Tons of liquid milk produced in the uk?
2. How many times a day are cows milked?
3. Parlour types?
4. How does the cluster work?

Answer 2

1. 11M tons.
2. 2 or 3 (more in robotic systems).
3. Rotary, herringbone, tandem/abreast, robots.
4. Applies reduced pressure (vacuum) to the teat end via the milking cluster.
   The collapsible rubber teat liner which surrounds the teat during milking is pulsated from the outside while the vacuum level remains constant so blood circulates to the teat. The movement of the rubber liner around the teat massages the milk out.

Question 3

1. What is the liner?
2. What is the teat cup?
3. What is the vacuum tube?
4. What is the claw?
5. What is the milk hose?

Answer 3

1. Rubber / silicone part in contact with the cow so needs changing every 2500 milkings (silicone lasts longer).
2. Houses the liner and space around the liner where a vacuum is created.
3. Creates pressure differential within the liner around the teat.
4. Where milk flows down into due to vacuum and pressure differential.
5. Where the milk flows through into the receiver jar.

Question 4

1. Production temperature of milk.
2. Bulk tank storage temperature.
3. Cool truck temperature.
4. Temperature of milk storage at factory.

Answer 4

1. 37-38C.
2. ~3.5C.
3. 3-4C.
4. 3-4C.

Question 5

What areas of the system could be of interest if the hygiene of the milk is not up to standard?

Answer 5

Parlour hygiene and storage of milk.

Question 6

How does bacteria get into milk?

Answer 6

Udder infection
- Depends on pathogens present on farm.
- Low number of cows likely to be infected at any one time.
Contamination during milking.
- Dirty udder
- Dirty cluster
- Dirty pipes
- Inadequate parlour cleaning
- Contaminated water source.

Question 7

What tests are carried out on milk to check cleanliness.

Answer 7

Residue testing.
California Milk Test / SCC.
Bactoscan – live and dead bacteria.
Total bacteria count (TBC) – live bacteria only.
Fat & Protein – health / nutrition.
Routine statutory disease surveillance e.g. Brucella abortus.
Elective disease surveillance e.g. Johnes, Neospora, IBR, BVD.

Question 8

1. Bactoscan.
2. SCC.

Answer 8

1. Indicator of on-farm hygiene.
   Identifies live and dead bacteria.
   Regulation 853/2004: milk with >100,000 cfu/ml not suitable for human consumption.
   Used in preference to total bacteria count in uk.
2. A marker of subclinical mastitis, and thus a marker of hygienic management of cow housing, and less of a marker of hygienic production.

Question 9

1. What could you catch from raw milk?

Answer 9

1. Campylobacter
   Salmonella
   E. coli
   Q fever (Coxiella)
   Listeria
   Leptospirosis
   Bovine TB

Question 10

Sale of raw milk.

Answer 10

Prohibited in Scotland since 1983.
Allowed in England, Wales and NI.
~200 license holders in England sell milk direct to consumers.
- At farm, market, delivery.
- Warning on bottle: ‘this product has not been heat-treated and may contain organisms harmful to health’.
- Higher hygiene standards.
- Inspections biannually.
- Milk sampled and tested quarterly to monito total bacterial count and coliforms.

Question 11

Types of pasteurisation.

Answer 11

High temperature for a short time (HTST).
- Continuous thermal processing method – indirect heating.
- Often heat exchange applied.
- 72-75C for about 15-20 seconds.
- Five “log reduction value” (99.999% or > in harmful bacteria.
- Colour and flavour maintained.

Ultra-high-temperature (UHT) processing.
- 138C for about 1-2 seconds.
- Combined with sterile filling technology.
- Milk can be stored w/o refrigeration for up to 90 days.
- May affect taste.

Question 12

Where is un-pasteurised milk still used?

Answer 12

Raw milk products popular due to taste.
Many cheeses made from unpasteurised milk.
Hard cheese: cheddar, Gouda.
- Mycobacteria can survive in cheese.
Soft cheeses.
- Listeriosis.

Question 13

Impact of hygiene on processing.

Answer 13

Many milk products made using bacteria for fermentation e.g. cheese and yoghurt.
Milk must be clean.
Bacteria already in the milk and antimicrobial residues influence processing.

Remnants of teat sealants used in dry cow therapy can cause black spot in cheese.

Herd level issues with ketosis can give milk a taint.

Specific components may be required e.g. higher butterfat for ice cream production.