I just finished slaughtering the smallest pullet out of the Cornish Rock "nuggets," which have been in the tractor for a month. First, her skin, membrane, and ligament integrity were excellent, to the point that skinning her took almost as long as plucking her would have. Both her crop and gizzard were full of grass, scratch, and crumble-paste, so she has been eating almost constantly while awake. She had very little fat on her, which is different from the nuggets I have raised previously. She had a beautiful, very dark red liver, a strong gizzard, and an average sized heart, which surprised me given her refusal to just slip quietly into unconsciousness.
She will make at least three dinners: tonight's stir-fry will have her breast meat, then the leg quarters will be another meal, with the rest of her carcass, wings, and giblets for at least one more meal.
Compared to the vast majority of other Cornish Rock pullets that hatch, she has had both a good life and a longer life. I have been in a commercial broiler house, and I have watched video of chicken processing in a plant ... and I have also worked the line in a few factories. The phrase "factory farming" is very appropriate for what your grocery store chickens go through. Cornish Rock pullets are normally slaughtered at five weeks, since their growth slows in comparison to the cockerels. You buy these labelled "Cornish Rock Game Hens," even though there is no game bird in their lineage and they are 47 weeks shy of being hens.
I'll post pics later - almost time to work the dough for bread now.