A note on the hog feeding idea,
Most pork in the US is contract fed, belonging to either the processor or a large contract grower.
The farmer is basically a contracted herdsman with little to no input on feed, feed rations, or ingredients.

Secondly, at this time corn is selling below break even and going down with the closing/shutdown of many ethanal plants. The hogs are bred and raised to exact feeding/feed factions for the absolute maximum "yields" at the slaughter house. These are not the hogs most people think about, a lot different than the hogs of 10-15-20 years ago.

Don't know how many fire members have ever been in a confinement hog building but I can tell you that if you threw green plants in front of most of the "residents" you would have sick if not dead hogs......if they even knew what to do and tried to eat them.

With the regulations for exporting pork to meet as well, contract growers would not be willing to take the chances.