Every day thousands of milk samples are collected from dairy farms across GB and delivered to one of the National Milk Laboratories (NML) for testing.
Angela Calvert visited the NML site in Wolverhampton to find out what happens when samples arrive.
NML handles bulk and individual cow milk samples. Bulk milk samples are collected primarily to facilitate statutory testing requirements set out by the Food Standards Agency, but they also undergo tests to determine constituents and quality.
This data is used by milk buyers for payment purposes in determining the farmer’s monthly milk cheque.
Alongside these standard tests, a further range of tests can be carried out, which provides farmers and vets with information which can not only benefit herd health, but can add value to their businesses.
Karen Bond, veterinary advisor at NMR, says: “While the processor is the primary customer for our bulk milk testing, we can use the samples to meet specific testing needs from vets and farmers to assist with herd health management.”
Both NML sites are in operation 22 hours a day, 365 days a year. They receive about 10,000 bulk milk samples every night, and up to 35,000 individual cow milk samples that have been collected as part of NMR’s individual milk recording service.
They start arriving when the night shift begins at 9pm and are all in by midnight.
On arrival, the barcode on each bulk milk sample is scanned. Service level agreements with milk buyers determine frequency of testing and what the sample is tested for. All samples are kept for five days, so if there is a problem, historic samples can be checked.
Bulk milk test reports are available by 6am, at which time farmers are sent a text with the results. Any failures or problems are followed up with a phone call to confirm the farmer is aware and the milker buyers also notified.
After five days, a milk sample is discarded, unless it is to be used for further disease surveillance which is scheduled in and done automatically.
Ms Bond says: “We are seeing an increase in the amount of sampling, which mainly is down to more awareness of disease and more demands from milk buyers and Red Tractor and advancing technology. The number of bulk milk samples is not changing, but we are testing for more things.”
Bulk samples are routinely tested for fat, protein, cell count, bactoscan, urea, antibiotics and freezing point depression (FPD).
The initial testing is done on a combi machine which takes a fingerprint of the milk including fat, protein and cell count, but can do much more, for example, measure fatty acids, lactose and in the future could even be used to predict pregnancy or disease. Usually, only a small amount of the data which is produced is used.
Bactoscans are done on a different machine, which will flag up non-specific bacteria, but will not show whether it is live or dead. This can be investigated further if requested, to drill down to identify specific pathogens.
Further testing may be carried out in the microbiology laboratory. Increasingly, testing for thermoduric bacteria, which can impact on the shelf life of a product, is being carried out and is now sometimes used as a payment parameter.
PCR testing is used for viruses and mastitis pathogens to identify the bacteria and cause.
Ms Bond says: “Individual samples from milk recording can highlight other things, such as energy balance, as well as disease which can be used to assist with nutrition and management.
“If you are milk recording and individual cow samples are being taken, you may as well make the most use of it and get as much information as possible from it by using it for disease of pregnancy testing. It also provides useful information to look at trends.
“We can test for things which can potentially add value to milk, such as fatty acids which impact on frothing, and saturated fats which is relevant when manufacturing dairy products.”
Milk testing facts
■ 19 vans, 15 routes, covering three million miles per year
■ All vans are temperature checked by linking to iCloud, which is more reliable than previous systems and can alert temperature failures
■ Individual samples can be sent direct from farm or moved by tankers or milk recorders; they are preserved so do not require cold chain storage
■ Vans deliver to two NML labs in Wolverhampton and Glasgow
■ One-in-400 samples fails for antibiotic residues
■ 150,000-160,000 samples are tested for Johne’s disease each month
■ Both labs are accredited by UKAS, which involves two-day lab audits at each site each year
TESTING for antibiotics on bulk milk samples is done by a robot using a Delvo plate and is carried out routinely, but the frequency depends on the milk buyer’s requirements.
If a sample fails, it is retested by heating, as an inhibiting substance can occur naturally in milk and heating gets rid of this, but still leaves the antibiotic, so it is a true test.
If the sample still fails, it is reported to the farmer and the milk buyer, which usually triggers an investigation and earlier samples can be checked. It is down to the buyer as to how to deal with it and what action to take.
As part of Red Tractor farm assurance, the vet has to be informed of any antibiotic fail.