They are not crazy about them..... Certainly not a treat.
The only reason that a small amount is added to feed, is to give the customer a very dark yolk....
Keep it a small portion of their diet, or you will end up with yolks that are not of an appealing color. It takes very little Marigold to get a very dark yolk. (We typically use 1lb per ton of mixed layer feed, for each step on the "yolk color fan"). If your birds are pastured, you would want...