Not sure as I have hanginging feeders but the industry figures a laying hen will eat 4oz of feed per day so for every four birds it would be a pound of feed roughly, as a sole ration. so a good rough guess would be 8-9 pounds of feed daily. I would break them up into smaller units so the stress...
Are you giving them supplimental feed or just grazing them on grass? If you are just grazing them chances are they are malnourished and that is what is doing them in.