Warm vs Cold Sampling of Raw Milk for Direct Microscopic Somatic Cell Counting

Area of Science:

• Dairy Science
• Microbiology
• Analytical Chemistry

Background:

• Standard Methods for the Examination of Dairy Products mandate cold milk sampling for bacterial and somatic cell analysis.
• Preliminary data suggested improved somatic cell counting precision when milk is sampled at 38°C instead of 0-4.4°C.

Purpose of the Study:

• To confirm preliminary findings on the effect of milk sampling temperature on somatic cell counting precision.
• To evaluate the impact of warming raw milk to 38°C on direct microscopic somatic cell counts (DMSCC).

Main Methods:

• Three technicians performed triplicate direct microscopic somatic cell counts (DMSCC).
• Milk samples were standardized to four different somatic cell count levels.
• Counts were compared between cold (0-4.4°C) and warm (38°C) milk sampling.

Main Results:

• Warming milk to 38°C resulted in slightly higher average cell counts across all levels.
• Grand average standard deviations showed a reduction in variability for warm vs. cold sampling at all levels.
• Improved counting precision was observed for somatic cells when raw milk was warmed to 38°C.

Conclusions:

• Warming raw milk to 38°C prior to sampling enhances the precision of direct microscopic somatic cell counting.
• This finding offers a potential improvement for routine dairy quality control procedures.
• Optimizing sampling temperature can lead to more reliable somatic cell data.