Many visitors here comment that my chickens look SO much more robust and healthy than any other chickens they've seen...but my chickens live off of restaurant scraps primarily, plus weeds, bugs, and seashell grit I bring home from the high tide line instead of expensive commercial chicken feed. I also occasionally give them probiotics like yogurt and kefir, plus routinely supplement their food with a few drops of tincture of iodine (Japan adds iodine to chicken feed to compensate for the Japanese eating much less seaweed in favor of American style fast food...the iodine goes into the eggs AND meat, and I am a BIG believer in iodine supplementation.)
I am comfortable eating eggs and meat from chickens fed restaurant food but realize some folks would not be. But I am a tightwad whose diet is SO not standard American fare, mostly organic and a great deal eaten raw right from the garden, I just don't worry if there is MSG or hydrogenated fat in some of what the chickens eat. And friends who eat all organic love getting surplus eggs from me.
I live close to a pizza buffet that daily sets in their dumpster a sealed bag of pizza taken off the buffet line at shift changes...it is easy to reach in, grab it, put it in my van, then give it to the free range chickens and the Coturnix quail in their huge spacious pen. The meat, veggies , cheese and crust gives them varied nutrition sources, as does the scraps I get from the dumpster of the Chinese Fusion buffet a hundred feet away. Both are at a mall I shop at weekly anyway, so I don't make any added trips to get the free chicken food.
Folks with chickens might ask friends, relatives and neighbors who work at restaurants, caterers, school cafeterias or grocery stores if they could trade fresh eggs for salvaged food destined to be wasted in a landfill. Attached is a pic of a bag of pizza that had just come out of the buffet in a brand new clean plastic bag, fresh enough to eat myself...which I HAVE done a few times!