As far as I know broodiness is a response to Melatonin. A chickens' melatonin is controlled by its Pinon gland. A very small pine cone shaped area of the brain that is excited by Sunlight. That is the main reason that a hen will lay during the Winter if her pinon gland is stimulated by artificial Sunshine (UV light). Both the hen and her rooster comes into their natural breeding season in the Spring when the daily hours of Sunlight and thus melatonin are reaching their highest. This will become obvious in the Spring when Both the roosters' and the hens' head, face, and comb plumps up and becomes bright red in anticipation of laying or in the roosters' case, assembling and defending a harem. At this time a hens' head will look like a very ripe and swollen strawberry. So i doubt that a hen will experience any significant decrease in her desire to sit, because she isn't in control of her own actions. Mother nature is. However at this time her chicks will have a smorgasbord of tender young insects, hen bit, and chick weed coupled with mild temperatures enabling them to grow up strong and fast. Also don't get suckered into believing that less is more when setting eggs under a hen. A full setting (15 eggs) have fewer swings in temperature and you will likely pip and hatch a larger % of your eggs at this time of year if for no other reason than the fact that the eggs are stronger and have a better mix of nutrients in the egg, and healthier or stronger seman from the rooster.
But as i tell everybody, those chickens belong to you so do with or to them as you see fit.
Edited by chickengeorgeto - 9/25/15 at 11:00am