The shorter a cow lives, the less time it will have to produce methane. Having done the math, emissions-wary beef producers in the U.S. are feeding their livestock a diet increasingly geared to rapid weight gain—including corn syrup byproducts and used oil from restaurant fryers—so the cattle can be ready for market earlier.
The 95 million cattle found on farms and feedlots across the United States contribute a large share of the country’s methane, and 2% of its annual emissions, reports the New York Times. So beef producers are moving their animals to feedlots earlier than they did in the past, both because grazing animals take longer to gain weight and because a grass diet tends to produce more methane.
While corn is an important part of the feedlot diet, beef producers “scour the market for other products that the cattle can eat,” the Times writes. “Depending on price and availability, this can include things like lint residue from ginning cotton, or ‘yellow grease’”—the latter being old restaurant fryer oil that has been re-rendered.
With such a diet comes a host of other problems, the Times notes. Because cows evolved to eat grass, their guts do not respond well to a feedlot diet, leaving them far more susceptible to illness (which, in turn, leads to overuse of antibiotics). Growing corn for feed also requires a lot of water, a particular concern in drought-plagued states like Texas and Kansas, where many of the nation’s largest feedlots are found.
A further problem: manure and urine from the cows is a significant source of nitrogen. In a grassy field, this nitrogen would be used by plants, but in a barren feedlot, it can do nothing except oxidize, producing a greenhouse gas that is 300 times more potent than CO2. And that’s beyond the systemic human rights and safety issues that often accompany Big Ag-run feedlots and their “large, windowless slaughterhouses,” the Times adds.
From the view of the meat industry, however, the picture is looking rosy. “Our system is exponentially more efficient than it was 40 years ago,” said John Richeson, a professor of agricultural business at West Texas A&M University. Such efficiency, he told the Times, “directly impacts the carbon footprint.”
Other adaptations the industry is developing include dietary supplements that would further inhibit the production of methane in the guts of cows. Meanwhile, in light of increasing resource scarcity and soil health, scientists at the EAT-Lancet Commission on Food, Planet, Health recently recommended a global shift to a plant-based diet, with a target of 50% less meat consumed by 2050, reports the Times.