The United States has long been the main consumer of meat, but as the environmental and economic repercussions of mass farming increase, there may have to be some changes, Mother Jones reports.

Most cows raised in the United States are fed corn and soy product along with chemical additives. Now the question arises of whether continuing this model of production or switching farming to a grass fed pasture would be better for the future of meat.

Although switching to the pasture model sounds more ethical, its effects are not sustainable and expensive. Judith Capper of Washington State University says that this would require "64.6 million cows, 131 million more acres of land, and cause 135 million more tonnes of greenhouse emissions."

The feedlot method is not sustainable either. According to ecologist Vaclav Smil, meat production around the world has multiplied by six, from around 55 million tons in 1950 to 300 million tons in 2010. To produce the animal feed, chemical runoff has created a large amount of ecological 'dead zones.' Smil believes that animals should be fed food waste and crop residue to cut the economic and environmental costs of feed production if the current meat consumption trends continue as projected.

In order for this to work, people would have to start eating less meat. In the United States, this is already happening slowly. In 2009, 9.5 billion animals were slaughtered, whereas now the number is around 9.1 billion. 

Smil also notes that people are consuming unhealthy levels of animal products. The current average, 209 pounds per year, is way above the healthy median of 100 pounds per year. With the switch from soy and corn to crop waste combined with less slaughter, this could balance out, but only if the developing world chooses to consume a more healthy diet.