Brian Goodwin

They can still reproduce, but the meat is out of the optimum growth range for the bacteria we worry about. Chemical reactions in the meat after slaughter drop it down to around 5.5 very quickly. Over time it creeps back towards neutral, so eventually the bugs can go to work. You still get growth on the surface of a cut though, lots of damaged cells there, so sanitary equipment is still very important. It's also easier to slaughter cattle and keep everything pretty sanitary. The anatomy of poultry is not as forgiving, and I guess no one in the US wants to pay for the extra effort.

I don't know about chicken liver specifically, but unspoiled beef is pretty acidic as far as meat goes. It's not a welcoming environment for bacteria to multiply, especially the farther you get from the surface of a cut. Chicken is closer to neutral, so microbes are more at home throughout the entire cut of meat.

Wikipedia mentions it here http://en.wikipedia.org/wiki/Gray_iron. I initially read it in a text book several years ago, but I couldn't tell you which. If you watch Lodge's How It's Made video, they mention carbon and silicon being added so they are definitely using an alloy, most likely a grey cast iron based on the ingredients. Some thermal properties are here http://www.substech.com/dokuwiki/doku.php?id=grey_cast_iron_astm_40. The thermal diffusivity should be about .151*10^-4 m^2/s based on those numbers. If you asked Lodge, they might give you their own numbers, since I doubt they use that exact alloy. Should be very similar though. Cast iron should still edge out carbon steel imo, so it doesn't change any of the discussion too much. The difference is minimal though, so a cook that likes carbon steel for reasons other than pure cooking performance won't be giving too much up so long as they chose a sufficiently thick pan.

I noticed a technical error with the article. It uses the material properties of iron, but cookware is not made out of pure iron, it's way too soft. Grey cast iron is what's most commonly used in cookware. It's thermal conductivity and diffusivity are similar to carbon steel.