Everyone knows that feed from haylage and corn silage bunkers will vary in composition from day to day. What is not so clear is the magnitude of this variation, and whether it might be worth it, economically and environmentally, to rebalance dairy rations daily to correct the variation. Providing excess feed likely will mitigate the effects of day-to­day silage variability, but this increases feed costs and is less environmentally acceptable. Many farms rebalance dairy rations weekly. A few attempt daily rebalancing. A better understanding of day-to-day variability of bunkers within a week is the first step to assess the potential benefits of daily rebalancing of rations. The most practical component to focus on for daily rebalancing is dry matter (DM) concentration; however, DM can be difficult to measure accurately, particularly in mixed haylage.