Explaining trends in Bulk Milk Somatic Cell Count from dairy herds in the Netherlands from 2018 - 2023

Area of Science:

• Animal Science
• Dairy Science
• Veterinary Epidemiology

Background:

• Bulk milk somatic cell count (BMSCC) in the Netherlands declined until 2018.
• An unfavorable upward trend in BMSCC has been observed since 2018, with a notable surge in 2022.

Purpose of the Study:

• To retrospectively analyze the factors contributing to the increase in BMSCC from 2018 onwards.
• To identify key drivers behind the sharp rise in BMSCC observed in 2022.

Main Methods:

• Utilized a multivariable regression model to assess associations between BMSCC and herd characteristics.
• Conducted a retrospective analysis of BMSCC data and related explanatory variables.

Main Results:

• BMSCC exhibits a seasonal pattern, peaking in summer.
• Increased adoption of automated milking systems, older cows, and larger herd sizes correlate with rising BMSCC over the study period.
• A doubling of milk prices and a shift in BMSCC testing calibration reference in 2022 partially explain the steep BMSCC increase.

Conclusions:

• While herd management factors influenced BMSCC trends, they do not fully account for the 2022 surge.
• Economic factors (milk price) and methodological changes (test calibration) are significant contributors to the recent sharp increase in BMSCC.
• Understanding these causes is crucial for implementing effective strategies to reduce BMSCC in dairy herds.