I used to weigh their feed before and after. I'm not well.How did you figure out how much commercial feed they eat vs. how much they eat free ranging? 40% in the winter is amazing. Do you know what it is in the summer, too?
I don't any more, mainly because I make a mash now and the water content varies day to day.
Some don't eat any commercial feed in the Spring and early summer. Once the ground bakes they eat more commercial feed than they do in the winter. There are a couple of reasons for this.
1) they tend not to lay eggs in the winter so don't eat as much,
2) When the ground is baked there are very few bugs and not a lot of green some years. They head into the woods in very warm weather and dig under all the pine needles and rotting branches.
Well, my view is if we didn't feel bad some of the time we wouldn't know what feeling good felt like.
Not much help am I.