Hello, I have 3 hens that I bought as 4 wk old chicks in late May. They are about 5 months old and still not laying. Should they be by now? So far none of them have shown any signs of it. I also have 2 hens that I bought. They're close to a year old and since the first day I bought them, they haven't laid at all. Is there any explanation for this? Anything I can do?