edited out my earlier comment, as I think Barnmaradotte's right about the regularly scheduled programming.
I have a mixed flock so I can't tell you what part of the feed goes to the chickens (I've also got turkeys, ducks, geese, guineas) and they free range all day, so they're suplementing their feed on their own. I feed a 22% crumble, scratch or cracked corn (depending on the price), and have oyster shell available free choice. the amount I feed depends on how quickly they clean it up after a day of foraging (I feed at the end of the day.) I put out 2 large scoops of crumbles and 2 large scoops of scratch or cracked corn and then see if they clean it up. if they finish it before they start to wander off, I put out another scoop of each. these are the large feed scoops you get at the feed store, maybe the size of a large coffee can. here's what I'm feeding with that: 5 turkeys, 4 geese, 11 ducks, 7 chickens, 5 guineas. I don't put out grit because they free range and should be able to pick up plenty on their own. they also get occasional table scraps, but we don't have much of that.
the second thing I track is their body condition... if they're staying in good weight, they're getting enough between foraging and feed to be fine. I bought the chickens as adults about 2 months ago, already laying, and they were really thin when I got them. in 2 months, while they haven't gotten to "fat", they've picked up some weight, and they are laying significantly larger eggs. the turkeys are in medium weight as are the ducks, and the geese are bordering on fat. the guineas are hard to tell... they're hard to catch and don't like being handled. these are all breeding stock birds, so I'm not trying to fatten them for fall meals, if I was, I'd put feed out all the time for the dinner birds.
it sounds as if you're feeding nearly as much as I am, and for far fewer birds. some of that difference is the free range factor, however I think you're probably feeding something besides chickens to go through that much daily.