Good article TC.
As a farmboy I feel I should pitch in a bit.
There are really three ways to raise livestock:
Pastured: Animals on open grass fields. Some additional grain and hay may be supplied
Dry lot: Animals raised in bare dirt pens. All grain and hay are supplied.
Confinements: industrialized. Automated feeding and very close quarters generally with no possibility of getting outside.
Roughage are the leafy greens of an animal's diet. Corn plants and alfalfa are the two leaders. Clover and oats also have a role as well.
Pork and chicken are so industrialized it is ridiculous. The industrialization doesn't lead to a much better product, but brings it about in a more efficient way. The tight quarters are ridiculous and make constant antibiotics necessary.
Beef isn't as bad, and with the collapse of beef prices in the 80s farmers generally quit trying to raise beef in as confined quarters as possible. Beef requires a lot of roughage. Even the roughage is often treated with antibiotics and simple preservatives. Their diet can be almost entirely roughage to about a 50/50 split by calories of grains and roughage.
Lamb is largely pastured. Their wool makes it very difficult to confine them. The largest dry lot lamb operation I know of is only 700 animals (a drop in the bucket). The price is prohibitive though.
The farm subsides need major re-working. The incentives to sell grain to ethanol producers have gone up and so now the price of most every livestock is going up. Farmers are turning back to alfalfa and other leafy crops to satisfy their livestock's needs for calories. Generally it takes 2 years for things to come around. The first year is to figure out what is wrong and fix it, second year the problem is actually fixed. The ethanol incentives might help the American food market take a step in the right direction.
One of the more popular antibiotics to feed livestock is aureomycin. Ever seen a semi full of pallets of 40 lb bags of antibiotics?
If you really want to see some of the supplements that go into livestock feed you might read through some of the literature here:
http://www.kentfeeds.com/...t-Selector.aspx I would discuss their products in greater detail but I cannot seem to load the details, think there is something wrong with this computer. That is the website of a medium sized manufacturer of livestock feeds.
I think I am going to start eating more fish.