They have cows with portholes, you know. Ag researchers really are interested in this stuff. We wouldn't have cheap, corn fed beef without science. Cows get sick on corn, and have to be fed antibiotics to survive. Cows were adapted to eat grass, but a grass fed cow takes ~5 years to get to market. It takes 1-2 years for corn fed beef to get to market.
Grass fed beef also has less E.Coli bacteria because E.Coli thrives in the acidic environment of a corn fed cow's stomach. Cows naturally have a basic environment. Here is a link to grass fed beef.
I am a crank about this stuff. ;)