Herd Composite Somatic Cell Counts: Average Linear Score and Weighted Average Somatic Cell Count Score and Milk Production

The relationship between herd production weighted average somatic cell count (average of somatic cell count weighted by individual cow milk production) and average linear score (average of individual cow linear score somatic cell counts) was investigated using three models. The model with the highest R² was log weighted average somatic cell count versus average linear score. Use of the regression model results to convert an average linear score to weighted average somatic cell count results in a bulk tank somatic cell count approximately twice that of conversion of a linear score somatic cell count when done on an individual cow basis. Rolling herd average milk decreased 190 kg as average linear score increased by 1.