What about feeding oats to chickens as well as corn??
I remember a guy who had horses that were kept in a field all year round. He said that he fed them crushed oats through the winter because oats keep them warm from the inside.
Does / would this work for chickens too??
The notion that corn and in particular oats are somehow "warming" is I'm affraid just an old wives tale (at least according to my professional animal nutritionist daughter). I guess this myth has been originated by the Scots Porridge Oats and Readibrek ("central heating for kids")adverts which portrayed oats eaten as a breakfast cereal as being warming. Indeed any warm food gives some warmth though not through it's food value just it's temperature. Oats and cereals being high in starch and fibre are less readily digested than refined foods and they are slower to release their energy than refined carbo-hydrates which are turned into blood sugar rapidly (known as high glycemic carbo-hydrates). Examples of high glycemic foods are white bread, pasta (particularly if cooked soft) and old potatoes (mashed potatoes). However whether slower release of sugar is a good thing for chickens is debatable. Having a full crop at night might be more or certainly just as important.
There's no need to feed chx warm food though provided it's not actually hot, just warm, there's no harm as a treat. There's no need to provide them with heated acommodation or hot water bottles either. Dry, sheltered housing is all that is required for all native breeds. lightly feathered or frizzle feathered varieties may need more care than tight feathered native breeds such as Sussex which are naturally more hardy. Obviously be more aware of really exceptionally cold weather and provide extra dry bedding otherwise they will cope fine without heat.
Best wishes
HF