UPDATE: April Fools!

Fast food mega-chain McDonald’s has just announced it will be making all its burgers from 100% grass-fed beef by the end of 2010.

McDonald’s is the largest purchaser of beef in the United States, serving more than 47 million customers daily. Since the company was founded in 1940, their beef has been supplied by feedlot livestock raised predominantly on a diet of corn and soy. As the first major fast food chain to make the shift away from traditional corn-fed beef, McDonald’s is hoping to be a leader in a new era of responsible fast food.

A spokesman for the company says the effort is motivated by consumer demand for safer, healthier products, as well as concern for the environment.

“The nation is ready for change and McDonald’s wants to be a part of the solution, not part of the problem.”

The new grass-fed cattle used by McDonald’s will also be free of antibiotics, which are only necessarily when livestock are artificially fattened on grains. Grass-fed cows are healthier and do not produce as much toxic waste as cows reared on feedlots, but they also mature more slowly. As a result, more time and money are required to raise grass-fed cows. McDonald’s acknowledges that this will result in a substantial 40% increase in the price of their burgers, but believes consumers are willing to pay for the added health and safety.

“Consumers are nervous about the increasingly dangerous problem of antibiotic-resistant bacteria that results when livestock are given large amounts of drugs, as they are on feedlots. By switching to grass-fed beef, we believe McDonald’s can play a substantial role in reducing this risk.”

The company is also aware of the positive impact this move may have on greenhouse gas emissions. It has been reported that nearly 20% of all greenhouse gases are produced by cattle, even more than are produced by automobiles and transport. They are hoping that their move away from corn-fed beef will encourage more environmentally friendly practices by the beef industry.

This new project is part of an ongoing effort by McDonald’s to offer more high-quality, environmentally friendly items to consumers. McDonald’s began serving organic milk in the U.K. in 2003 and premium coffee was added to U.S. menus in 2006. But the switch to grass-fed beef is by far the most significant “green” change any fast food chain has made to date.

The shift has only been announced for U.S. restaurants, but insiders suggest grass-fed beef may reach global consumers by 2012.