we think there is a difference if they have been off feed for 8-12 hours. ESPECIally if there is paileen in the feed. but even if there isn't... any less time and they are too comfortable in their pen... any longer and they are high strung because they have been off feed too long. 8-12 hrs of empty feeders seems to be the sweet spot where they are hungry enough to get up and move around but not so hungry that they become grumpy