Why aren't they laying?

[SaintRiven]

8 months old, were laying well till 3 weeks ago. Food is going in one end and nothing but poo coming out the other. They aren't broody or moulting.
why?

Probably just because the days are shorter now and they're not getting as many hours of daylight. Ours stopped laying at about this time when they were in their first year of laying, and they weren't moulting. They started up again about January/February time.

What breed are they? Some are more prone to going out of lay during the winter than others.

what breeds are they? hybrids are supposed to lay throughout the winter but pure breeds stop laying int he winter.

Are you sure that nothing is stealing the eggs - rats, snakes, neighbours? Have the hens been upset recently? They may just be having a short rest from laying (ie. like during the moult but without actually moulting). Or perhaps they are going to take the winter off - which would be very inconsiderate of them.

If you're bothered by it, you could try increasing their diet, or add some energy-rich corn if they don't usually have it. Or even a daily scattering of sweetcorn with a little cod liver oil on it. It may boost their overall condition enough to put them back into lay. Do they have enough oyster shell? Are they coming out early enough in the morning, going to bed at dusk?

Btw, my pure bred Sussex hens have always laid through the winter.

Sorry - Must hijack conversation here - what is oyster shell? Have I missed something basic?

I am waiting for my buff orpingtons to start laying they are 25 weeks old and being fed on layers pellets and occasional corn?

Crushed up oyster shell (very cheap - from pet shops, feed merchants, etc) provides the hens with calcium - both for them but more importantly, for making egg-shells. They get a small amount of calcium from free-ranging but if they don't have enough of it in their systems, they will draw it from their bones to make shells which considerably shortens their lifespan.

Either have it available in a grit hopper on it's own or mix a small handful to their food hopper. I keep my hen food in a dustbin and just mix it altogether in one go so I don't have to bother doing it separately or forget to add it!

I'd start giving it to your Orpies now as they will be laying very soon. The first few eggs may be shell-less or 'soft' shelled btw, that's quite normal and nothing to do with not having enough calcium.

Do your hens also have hard grit (small stones, bits of flint etc) for grinding up food in their gizzards?

the only grit they would get is whats in the soil?