Monitoring of ruminating activity in cows can help detecting deficiencies in structural fibre in the diet and also identifying related rumen disorders at an early stage. The aim of this study was to evaluate a noseband sensor system (NSS; “RumiWatch”, Itin+Hoch GmbH, Liestal, Switzerland) under variable feeding regimens. Visual and electronic measurements of ruminating activity were compared in eight Holstein cows fed either roughage-only diet, transition diet from roughage to concentrate, or constant feeding of 65% concentrate (dry matter basis). Increasing the concentrate amount in the diet lowered (P
