Ihave lost 4 hens in the last 6 months .They just stand around with their eyes closed. The last hen I cut her craw open to find it full of pine shaving and grass so I clean all the nest out and put straw in them hoping that would fix the problem now I have another hen doing the same thing.They are production red hens about 1 1/2 yrs old good health, free range, locked up at nite , let out during day. I bought the hens from a man that had them locked up but that was 7 months ago so the grass should not be the problem or?Any ideas?