I have two different ages of chickens the one pen they are about 1 year old and the other pen they are just pullets. Last month the pullets were only giving my about 3 eggs per day they had already been laying for about 2 months (I have about 20 birds) they stopped about 2 weeks ago, the 1 year old's were giving my 15 to 20 eggs per day (20 birds also) the egg production slowly went down until last week they stopped laying all together I haven't got one egg in a week. One of the pullets is still laying but I have a big family and we pretty much live off eggs and this is a pretty hard on us! I ran out of oyster shell for about a month and got some yesterday and am starting to feed them it, does that have anything to do with it? I also don't have a light on in the pullet coop cause they are still in the movable pen because we are in the middle of building their coop (we have been so busy mucking out barns fixing cars and building a silo! This year has been hard) so the coop is being put off but will hopefully be done by middle of December but until then they won't have any light. The 1 year old hens have a light and they still aren't laying. I am going to start de-worming them cause that might be part of the problem. But I have raised chickens like this for years (sometimes going without oyster shell for 5 months) and we have never in 10 years had this problem. Any advise would be greatly appreciated!