Can I use old feed bags on the floor to put feed for my baby chicks?

This is not ideal at all. Old feed bags may, to begin with, have fungal growth on the old leftover feed particles. Chicks will ingest this fungus and may become infected. Feed bags are also not very good at retaining feed - baby chicks habitually scratch at the feed and tend to scatter it outside the boundaries of the container it is placed in. Paper offers no resistance to scattering, while shallow pans or feeder trays have a lip that deflects scattered feed and retains it. Scattered feed is then picked up out of the litter by the chicks, often after it has been there for a while collecting more fungal growth… mold and fungal infections are common where feed scattering into the litter is a problem. Ideally feed should be presented to baby chicks in our plastic feeder trays, 1 tray for every 100 baby chicks being placed.