Don't worry, they will eat it. they are "CHOOSING" not to since you free range them. When push comes to shove (cold months or you keep them penned for a few days) they will gladly and hungrily gobble this down as well as anything else you toss them. It is no problem for them to swallow and has less dust than crumble. I have a variety of animals at my place, grind up a special feed for my baby and young quail a 29% protein feed with added goodies. Add to this the dust from the chicken feed, a scoop of rabbit feed, oyster shell, food grade DIO EARTH, some laying pellets, and feed the whole mess to my ducks. They gobble it down, of course the chickens need to try this out as well while the are out in the yard, daily. My chickens will not hardly touch snow by the way. I have a fully covered 4x12 run, leading to their big yard. I could easily fit a 24 foot pool in this area.
I have seen my chickens pick bones clean I give to my cats to chew on, what the cats can't get at, the chickens do. Nothing is wasted at our place.
Heck, if I could find a way to grind bones, I would even offer that as well as put it in my compost. In the cooler months, I add blood from the processed rabbits to my compost. I could dig it in in the summer I guess. To dang tired and hot most of the summer though.