Somatic Cell Reference Samples for Calibration of Milk Somatic Cell Counting Methods.

Area of Science:

• Dairy Science
• Analytical Chemistry
• Veterinary Diagnostics

Background:

• Accurate milk somatic cell counting is crucial for dairy herd health and milk quality assessment.
• Standardized reference materials are needed to ensure consistency and reliability in somatic cell counting methods.
• Existing methods require reliable calibration standards for accurate performance evaluation.

Purpose of the Study:

• To develop and validate stable somatic cell count samples (SCCS) for calibrating milk somatic cell counting methods.
• To assess the stability and reliability of SCCS under various storage and transport conditions.
• To establish SCCS as dependable reference standards for common milk analysis techniques.

Main Methods:

• Raw bulk milk was preserved with potassium dichromate.
• Somatic cells were isolated via centrifugation and diluted in preserved skim milk.
• SCCS were stored at 4°C and tested for stability over 23 weeks.
• Bacterial contamination was assessed.
• A collaborative study involving eight laboratories evaluated SCCS during shipping.

Main Results:

• Somatic cell counts in SCCS remained stable for 23 weeks when stored at 4°C.
• No bacterial contamination was detected in the prepared SCCS.
• SCCS were unaffected by typical shipping conditions in a multi-laboratory study.
• The developed SCCS demonstrated suitability as reference standards.

Conclusions:

• Potassium dichromate-preserved SCCS are stable and reliable for milk analysis calibration.
• These SCCS can be effectively used as reference standards for direct microscopic, Fossomatic, and Coulter Counter methods.
• The developed SCCS offer a practical solution for ensuring accuracy in milk somatic cell counting across different laboratories.