We also had your problem until we started using a bucket feeder. It ends up costing $30 if you don't have the tools to do it, but you make it up in feed.It's a 5 gallon bucket with 4 holes we drilled in it, and we stuck four 3" 90 degree street elbows in the holes. Now the chickens have to stick their head down in the elbow to get the feed. Hope you solve your problem.
Edited by Lynn Manes - 9/8/15 at 3:15pm