Comparison of an image cytometry somatic cell count analyzer to a flow cytometry analyzer

Area of Science:

• Veterinary Diagnostics
• Dairy Science
• Biomedical Engineering

Background:

• Somatic cell count (SCC) is a key indicator of bovine mammary gland health.
• Accurate and accessible SCC testing is crucial for dairy herd management.
• Traditional flow cytometry methods are laboratory-based.

Purpose of the Study:

• To evaluate the performance of a benchtop image cytometer (LactiCyte HD) against a standard flow cytometer.
• To assess the accuracy, precision, and diagnostic capabilities of the image cytometer for somatic cell counting in milk.
• To determine the optimal image resolution for the image cytometer.

Main Methods:

• Milk samples from routine dairy herd improvement (DHI) testing were analyzed.
• Samples were split for analysis by flow cytometry (regional DHI lab) and image cytometry (16 and 8 images per slide).
• Concordance correlation coefficients, bias, sensitivity, specificity, and coefficients of variation (CV) were calculated.

Main Results:

• The image cytometer demonstrated high concordance (CCC > 0.95) with flow cytometry across both imaging resolutions.
• Sensitivity and specificity for detecting subclinical infection (≥200,000 cells/mL) were high, particularly at 16 images (92.0% and 91.7%).
• Method precision (CV) was generally better with 16 images compared to 8 images, especially at lower cell counts.

Conclusions:

• The LactiCyte HD image cytometer is a suitable analyzer for on-farm somatic cell counting.
• It can be effectively used for screening cows for potential mammary infections.
• Optimal precision and diagnostic accuracy are achieved when utilizing the full image analysis capacity (16 images).