A link to several pictures, still on chickens:
http://www.ca4a.org/bbc/photos/?file=C

That is disingenuous. What is the ratio of adult to newborn weight in chickens v. humans, and at what age is a chicken fully grown v. 16 to 18 years for a human?

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman

In the US, breeding has become so extreme, that most factory-farmed meat chickens (called 'broilers') are a 4x hybrid. The hatcheries sell what they call grandparents. These grandparents in turn produce chicks which are again crossbred to produce the modern broiler chicken.

The US produces more than eight billion meat chickens each year. The large producers contract out the actual raising of the chickens to small farmers. The small farmers have large sheds and the producers bring them feed, 10 - 20,000 hatchlings for each shed, and then collect the chickens when they are 4-5 weeks for what is called "Rock Cornish Game Hens" or 7-8 weeks for standard broilers. The Rock Cornish Game Hen named product was invented by Tyson Foods in the early 1950s as a way to distribute young, frozen standard meat chickens.

Spent (old) grandparent and parent broiler hens are sold to canners for soup, or other meat products. In the US, spent factory egg-laying hens, which are much smaller than meat hens, are often destroyed. Canners pay only $.10 to $.16 per chicken delivered, the cost of delivery alone from rural egg-laying areas to more urban canneries is cost-prohibitive.