The feed will have the age listed on the bag.
Also, there is usually a "grower" food to be used in between starter and layer food.
No. Hens that are "too old to lay anymore" would make very poor market quality chicken. Slaughterhouses that process chickens for the food industry get their chickens from farms where the chickens are raised specifically for the meat market. "Overage" layers that are sent to slaughter wind up in cat food, etc.
The first course follows starters in a menu.
the food that babies start off with
Oh, sure. Chickens are a very common food item.
Yes, they most certainly do. It's a form of digestive distress - a common reaction almost all chickens will have. It should clear up in a few days; if it doesn't, switch back to the old food.
Chickens eat grians,some wheats and corn.
No it's not. There are things that need to change. For starters roaches. They need to be exterminated. Leaks when it rains, who wants contaminated food?
Dumplings can be used as appetizers, meal starters or just a dish with the rest of the food.
Chickens produce eggs and meat.
poo pee eats prairie chickens.
assuming by "they" you mean the farming industry, they would use a high protein grower food for the meat birds and for the layers they would use layer pellets
You can feed chickens dog food; chickens are omnivorous and eat almost anything. The only drawback to feeding dog food to chickens is that it is more expensive than feeding them grain and other purely vegetarian type food.