In my opinion, based on quality of growth and eggs, when forage is of excellent quantity and not limiting I cannot beat it with a commercial feed. Keep that in context that commercial feeds are more nutrient dense and can be easier for birds to consume. There are times with some poultry keepers that birds that have to work for their grub are better as a finished product. For me this means muscle tone, feather quality, hatch-ability of eggs, and longevity assuming you do not have a predator issue. I would not extrapolate that to Cornish X or any of the egg production breeds, including Leghorns that are selected for performance on nutrient dense feeds.Forage is better than commercial feed?
What must always be considered is how much and the quality of the forage. It is easy to have more birds than the landscape can support, especially when we are using a feed to keep them concentrated in area to point the forage base collapses.