Fig. 2From: Evaluation of farm-level parameters derived from animal movements for use in risk-based surveillance programmes of cattle in SwitzerlandThe January cohort followed over one year. The proportion expresses how many cattle were still in the same herd on the 1st of every month in 2012. Over the summer month, the proportion of animals leaving the herd increases because entire herds are moved to summer pasture. The increase of bovines originally in the herd in October is due to cattle returning from summer pastureBack to article page