Understanding laboratory Jargon

TVC: Total Viable Count

A TVC is not a specific micro-organism but rather a test which estimates total numbers of viable (viable means living) individual micro-organisms present in a set volume of sample. The TVC count may include bacteria, yeasts and mould species.
Clearly it is impossible to have a set of conditions that are ideal for all organisms likely to be present in any one sample. This should be borne in mind when interpreting the results. TVC results are however very useful for trend analysis whereby changes in the numbers of microbes present in a system can be monitored over time and multiple samples. Mastitis
Mastitis is an inflammation of the udder, typically caused by a microbiological infection.

Total Bacteria Count (TBC)

Low levels (<50,000/ml) are essential to ensure the manufacture of high quality milk as directly increases the shelf life of milk and allow the Society to manufacture the highest quality final products for our customers. High levels of TBC are an indicator of on-farm general hygiene conditions, milking equipment cleanliness and milk storage (temperature and time).

Somatic Cells
Somatic cells are cells from the cow (predominantly white blood cells, otherwise known as leukocytes) that are normally present in milk. During most mastitis infections, the number of somatic cells present in the udder increases to help the cow fight the infection. There are several types of somatic cells that have different functions in fighting infection. Somatic cells can contain lipolytic and proteolytic enzymes, which degrade fats and proteins, respectively. An increase in somatic cells count during a mastitis infection increases the amount of destructive enzymes present in the milk, which increases the rate of deterioration of the milk fat and protein.

Bacteria Count
The total bacteria count is the number of bacteria in a sample that can grow and form countable colonies on Standard Methods Agar after being held at 32°C (90°F) for 48 hours.
Coliform Count
The coliform count is the number of colonies in a sample that grow and form distinctive countable colonies on Violet Red Bile Agar after being held at 32°C (90°F) for 24 hours. Coliforms are generally only present in food that has been fecally or environmentally contaminated.

have developed mechanisms to resist heat and other lethal agents such as sanitizers. Most of these bacteria have an ability to create a protective form called a spore that is very tough to kill.
The spores end up in finished products and begin growing and damaging the milk product. The most effective way to minimize the LPC count is to prevent contamination of the milk with thermoduric bacteria. This means clean cows and clean equipment. Thermoduric bacteria are common in soil and fermented feedstuffs. When cattle are exposed to contaminated material, thermoduric bacteria get on their teats. Poor udder sanitization will allow problems to develop. Milkstone buildups in the system may protect some of these bacteria and allow them to multiply in the raw milk. The LPC test is a good estimate of both cow and system cleanliness.

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