GARBAGE IN, GARBAGE OUT:
Sort of off-topic, but on the subject of spent hens being made into pet food, I just read an article in Mother Earth News about what 99% of commercial cows are being fed these days. Some horrifying things there, including spent hens ground up with "poultry litter"!!!!!! So your supermarket beef is fed chicken shavings, poop, feathers, and old hens. Actually that is the least disgusting. They cited a farmer who fed 30% of the diet as "stale chewing gum, including aluminum wrappers". Others fed a 100% "old french-fry and tater tot" diet. Others fed stale candy bars, stale pizza dough. And UREA. And even heat-treated garbage is allowed by the USDA as suitable feed for the beef you buy at the supermarket. They do not require producers to tell consumers what the animals were fed.
From the "Journal of American Science" study: stale chewing gum in its wrappers "can safely replace at least 30 percent of cattle-growing or finishing diets without impairing feedlot performance or carcas quality" 
YUCK YUCK YUCK
I am SO glad we bought our grass-fed cow last fall!
(Olivia says: "I am so glad that I don't eat that kind of meat anymore!")
(Stacey says: "I'm sorry to all the moms of Olivia's friends who she is sure to tell this to. Thier kids will be complaining about dinner.")