Here is a good blog about it. https://the-chicken-chick.com/the-shocking-effect-of-oatmeal/Just read article on chicken treats which included hot oatmeal. In winter, I used to make it every morning for my feathered family along with Kefir, which I make and give them everyday. However, I read an article, posted in one of your forums, which stated that hot oatmeal is too glutenous for them to digest properly and is more harmful than helpful to their digestive tract and absorption.
Now I'm not sure what to do, because they did love that warm tasty breakfast in the cold weather.
Information came from poultry nutritionist not the blogger herself. Oatmeal does have a type of fiber that can cause issues for chickens if given too much. You are also diluting there total daily nutrition. Your better off giving pellets or crumble with a little kefir or warm water.
This is not the first time I’ve heard a poultry nutritionist to say oats should be used sparingly as a ground powder to increase fiber only, they really have no other nutritional value. I just listened to a podcast that explains they are prickly they can cause issues with the intestines when not ground.