I can sure tell if my hens have been on the grass you might say we live in the mountains and during the winter they are almost totaly on feed but in the spring and summer they get to eat what they want end the eggs sure tell the differance
I have a big buff that will take care of your problem. I keep him away from the hens. check your water supply some water has a chemical leeched from plastics that is known to couse sterility in birds