hey guys! i am going through a lot of feed for my birds. i only have 4 ducks and 4 chickens. how much should i be feeding them. they are getting around 16 cups a day if i were to measure it out in actual measuring cups. they get greens daily and free range in the backyard from sun up to sun down.... they are cleaning the plate. i have never seen wildbirds in it or squirrels thank god! they do not look fat either... idk what to do. its expensive!