After milking, a sample of the milk is taken and transported to a lab for testing - what are the samples tested for and how do the results impact the farmer and processor?

Milk samples are tested in a laboratory for nutrient composition, quality and safety. 

After milking on an Australian dairy farm, milk is stored and cooled in a vat (refrigerated stainless-steel tank) and gently agitated (stirred) to ensure an accurate sample can be taken.  

The tanker driver arrives to collect the milk within 48hrs of milking and takes a representative sample, which is transported to the processor’s accredited laboratory for testing.  

The milk sample undergoes several types of tests:  

• Milk composition (fat and protein): Processors measure fat and protein to understand the natural nutrition of the milk and its value for making products such as cheese, yoghurt and butter. Milk with higher levels of these natural solids (fat and protein) have a higher value, and farmers receive a higher payment when their milk contains more of them.
• Microbiological quality (bacteria levels): Bacteria levels are assessed to ensure the milk has been collected, cooled and stored hygienically. Low bacteria levels indicate safe, fresh milk that is suitable for processing, while high levels can spoil milk, affect flavour, and create food safety risks. 
• Cell count (somatic cell count): Cell count is monitored to understand udder health in the herd. A high cell count can indicate mastitis (an infection in cows), which affects milk quality and taste. Milk must meet legal cell count limits. If it exceeds them, it’s usually discarded or sent for non-food uses. These results help both processors and farmers maintain animal health and product quality.  
• Antibiotic or chemical residues: Milk is tested to ensure no antibiotics are present, in line with strict food-safety regulations. Milk must be free from detection of these substances before it can be processed and sold.  In some cases the milk sample may also be included as part of an Australian Government survey to monitor the presence of any chemical residues which may result from improper use of cleaning products or other on farm chemical use. These results enhance Australia’s high dairy food safety reputation and support Australian dairy product value in international trade.