What could cause thick (tough) egg membranes? Last year our eggs had this problem and I'd like to avoid it this year. I did a little research and found that humidity levels that are too low during the last part of incubating can cause tough membranes and hatching problems. I would say that could have been our problem -except- that all our 'eating' eggs also had tough membranes. It wasn't easy getting through the membranes when cracking the eggs open. Shells were fine - not too hard or too thin. Could it be a feed issue? Last year I fed them a 16% protein feed mix of whole oats and 24% feed - no free ranging because of a fox problem. Now they're getting chopped corn & whole oats (corn>oats) with free ranging (fox moved on), and the eggs are fine. Just don't need this problem again - any suggestions? I read somewhere that too much oats was 'bad' for chickens. Any possible connection?