Short communication: contribution of vibration and noise during milking to the somatic cell count of milk.

We investigated the hypothesis that somatic cell counts (SCC) in milk are influenced by the vibration and noise experienced by dairy cows during milking. We therefore measured vibration and noise on 50 Swiss dairy farms (with herringbone, autotandem, side-by-side, or carousel parlors), where we also collected bulk tank SCC. Somatic cell counts increased with an increasing intensity of vibration but not with acoustic noise. Cows milked in autotandem and side-by-side parlors had lower SCC than those in the other 2 types of milking parlors. On 12 farms where the milking system was modified to reduce vibration and noise, SCC also dropped. In addition, the relative improvement in SCC seemed to be correlated with the relative improvement in the reduction of vibration but not with the improvement in acoustic noise. A reduction in vibration (structure-borne sonic waves) seemed to improve udder health, which may have been mediated by the increased well-being and reduced stress of cows during milking.