The people I know are confused about what cows eat. The idea that they might eat grass sounds right, and the idea that they might eat corn also sounds right. The idea that corn is not part of a cow's natural diet does not sound right to most people. Most cattle in 2009 do eat corn, so it's logical to assume that corn is a natural part of their diet.
But a modern cow's diet is not about nutrition or evolution. It's about economics.
During WWII the U.S. government built 10 new plants to provide nitrogen for bombs. After the war, those plants were converted so that they could produce nitrogen fertilizer. Officials were excited about the productivity the fertilizer would provide, and it flooded the market. At essentially the same time, modern irrigation and modern pesticides hit the agricultural scene. The corn yield tripled immediately, and the price of corn plummeted far below the price of grass.
Even in our era of ethanol innovation, corn is heavily subsidized by the government, keeping the price (superficially) low. And that, my friends, is why most U.S. cattle eat corn.
It is true that farmers historically "finished" cattle on corn or other crop surplus to fatten them before slaughter. But a full diet of corn is vastly different. Cattle who feast on only corn after weening are disease-ridden and grow big at unnatural, unhealthy rates. Some industrial cattle farmers further cut the corn feed with foodstuffs such as candy and municipal garbage. By the time of death, the cows' livers are nearly destroyed, and they've been dosed with an overuse of antibiotics - partially to combat an immune system weakened by a synthetic diet.
In my next post I'm hoping to explore the various ways to support your local renegade pasture-grazing cattle rancher a.k.a. "livestock superhero."