Providing a commercial service of certified reference milk for calibration of milk somatic-cell counting instruments.
Driver for the research
In response to the introduction of penalty payments for milk with elevated counts of somatic cells, the Department of Economic Development, Jobs, Transport and Resources (DEDJTR) was funded by industry to develop standards for the calibration of equipment used to count somatic cells in milk, both bulk and individual-cow samples.
Somatic cells in milk are leucocytes (white blood cells) and are one indicator of milk quality. The number of somatic cells increases in response to pathogenic bacteria which cause mastitis.
Milk with somatic cells below 250,000/ml is considered good, while above 500,000 indicates serious problems with mastitis. Milk companies impose financial penalties on suppliers when bulk milk rises above a threshold, commonly around 250,000 somatic cells per ml.
These standards are necessary so that results from all laboratories are comparable and dairy farmers can be confident in those results.
Research by DEDJTR Ellinbank staff resulted in:
- An identified need for milk with three concentrations of somatic cells for calibrating instruments.
- Long shelf life of the standards through the use of heat treatment.
- An understanding of the effect of preservative and heat treatment on the efficacy of counting of somatic cells.
- The use of a ring test process to generate certified reference values via consensus.
- The standards being packaged in small, foil sachets so they were cheaper to produce and ship.
- Packing and shipping protocols to ensure the standards arrived chilled, even if delivery took one week as is possible for overseas deliveries.
The current objectives are to:
- Identify and source natural milk at three concentrations of somatic cells for the production of Low, Medium and High standards.
- Package and dispatch the standards four times per year.
Milk for the standards is sourced from cows at the Ellinbank Centre. A preservative, to reduce spoilage, is added. Milk with different concentrations of somatic cells is mixed to achieve the target milk with Low, Medium and High somatic cells.
Milk is supplied in foil sachets of 30 ml, as untreated and heat treated, to meet client requirements.
Untreated standards have a shelf life of 18 days from collection. The heat-treated standards have a shelf life of 90 days.
All standards are stored at 4°C, and transported on ice to maintain their shelf life.
Access to the standards is via quarterly subscription plus a fee per set of standards. A set consists of one sachet of each of Low, Medium and High. Most clients use one set per day of operation.
Reference values are published to all clients 14 days after dispatch, with those clients who return their results receiving an interim value 7 to 14 days after dispatch.
Monthly and quarterly reports are provided to all clients as part of the service.
Subscriptions and fees
This Project is funded by subscriptions to the service and fees for the product.