You're Probably Drinking Cannibal Cow Milk

As milk prices hover at record highs, dairy farmers are hard-pressed to squeeze every drop of milk out of every available udder. Cows need energy, and one popular way to power their rampant milk-making is to feed them tallow—recycled fat from other cows.

Not only can melting some fat into cow feed increase milk production, improve fertility, and reduce the dustiness of all that grain, but feeding cows the greasy remnants of their butchered brothers actually upsets their stomachs less than vegetarian options like sunflower seeds or cottonseed, which can bother their delicate ruminant innards with their unsaturated fats.

Modern dairy farmers constantly sort through the prices of different feeds to improve their bottom line, and tallow is an old favorite. If a famer is buying fat, what he's really buying is energy, said Dr. Kevin Harvatine, assistant professor of nutritional physiology at Penn State. It can come in the form of corn, byproduct from bakeries, or a barrel of congealed cow fat, but each choice has its own economic logic and its own health effects, he said.

"It can be a cup of corn or a cup of fat," said David Meeker, vice president of the National Renderers Association (the other, lesser-known NRA). "The spike in feed prices and pressure on productivity because of milk prices have sent them back to the books and looking at all the alternatives."

This soylent-green-like practice is nothing new. It used to be that when a farmer came upon a dead cow, pig or chicken, or when a municipal worker came upon a splattered armadillo, or when a kill shelter needed to rid itself of piles of euthanized dogs and cats, they would take their animals to the local renderer. At the renderer, the animal corpse is pulverized and melted to its constituent parts—proteins, fat and —which would then be refined and re-enter society as soap, candles, crayons, and other products.

Without this ancient industry, proponents note, we would be dealing with nearly 60 billion pounds of animal bones, blood, and viscera, as well as the 4 million cattle, 7 million pigs and 100 million chickens that die as a matter of course on farms each year in the United States. All those dead animals would just have to be wasted in our already overflowing landfills. According to the NRA, we'd all be drowning in rotting offal within four years.

"Fat is very important in the feeding of the animal, and we use a lot of different sources—basically whatever is most economical," said Dr. Chad Risley, CEO of food and feed ingredients company Berg and Schmidt America and a swine nutritionist by training. "Everyone views the farmer as a hobby farm with a couple chickens and a cow and a pig, and that ain't the way it's done anymore, and it can't be done that way in order to feed everybody."

It was in the early 1900s that agriculturists first began using rendered fat to feed America's livestock. Until then, it was used mostly for soap, and before that, candles. In 1950, only two percent of all inedible tallow and grease was used in animal feed. As soap manufacturers transitioned to synthetic sources, the rendering industry adapted. By the late 1990s, cows, pigs and chickens were consuming more than 70 percent of all inedible tallow.

Likewise, the use of ground animal protein—meat and bone meal (MBM)—was "discovered" in the early 1900s and took off around World War II. Soon, nearly all of the approximately 8 million tons of animal protein produced each year was going into animal feed. Those were the glory days of agricultural recycling. Tech advancements even helped rid rendering plants of their notoriously bad smells.

Then, in 1986, cows in Great Britain started stumbling around and dying. The infectious proteins that cause Mad Cow Disease (bovine spongiform encephalopathy, BSE) could withstand the intense heat of the rendering process. By 1997, authorities stepped in to ban the practice of feeding cow protein to cows. A blossoming MBM export industry collapsed. Today, the vast majority of rendered protein goes into pet food and chicken feed.

Of course, it's still okay to feed cows protein collected from pigs and chickens. It's also okay to continue to feed cow fat to cows, as long as it contains less than a strict maximum in insoluble impurities. But the fallout from BSE and the media firestorm that followed continues to stigmatize tallow, a trend that has led some feed mixers to favor vegetable fats over animal fats. That trend has more to do with public perceptions than the health of the animals, said Dr. Risley.

"I personally have an issue with people who want to feed all vegetable instead of a mixture of vegetable and animal," he said. "It's just marketing and consumer demand. People were turned off when they found out that cows are eating cows. I would say that cows are eating nutrients, it doesn't matter where they're coming from."

Despite such demonization, about half of all rendered fats and greases (36 percent of which is inedible tallow) still go into animal feed or pet food, and about a fourth of all fat feed goes to cows. Rendered fat remains, according to a 2011 survey, the primary source of fat in most livestock rations, and tallow use in feed, food, and industry was up 4 percent overall in 2013.

The fat market has also found itself in the throes of strong demand from a brash newcomer in the market for processed fat by-products (or "co-products," the preferred term in the industry, since the fat and protein gained is valuable, just like the steak that comes with it). US biofuel production has exploded in recent years, growing from 300 million gallons in 2000 to nearly two billion gallons today and threatening to drive up fat and feed prices. Over the last five years, biofuel has consumed half a million metric tons of rendered fat that would have otherwise ended up on the export market.

Markets may change, but rendered products will remain a crucial ingredient in animal feed for as long as they present an affordable source of energy and protein for farmers, said Meeker.

"Nutrient building blocks are nutrient building blocks," Meeker said. "Fat is fat and protein is protein. Rendered products are broken down to their basic parts and they're proven safe."

While feeding cows their own fat may seem dystopian, unnatural, and somewhat sinister to many non-agriculturalists, here's some apologist math from the NRA to consider:

The world's population is growing by more than 200,000 people each day, and demand for milk and meat are also growing fast.

Animal fat contains more than twice as much energy as grain, so replacing all the animal fat in our livestock feed would require more than 474,000 truckloads of corn each year, or another three million acres of corn production. Replacing the protein used in feeding would require 12.2 billion pounds of soybean meal, which amounts to 11 percent of all the soy protein produced in the United States. Together, all that protein and energy would require about a third of all of Iowa's farmland.

Hence the most convincing argument for turning a blind eye to all our cannibal cows, chickens, and pigs: Without their insatiable hunger for their own kind, our food would be much more expensive. Many of us wouldn't be able to afford a steak, a glass of milk, or maybe even a can of corn, to begin with.

In its own weird way, rendering is America's original green industry. It not only directly supports the production of biofuels, but it prevents overuse of farmland, reuses natural resources, and keeps food affordable. We consume this stuff every day and, like our cows, we don't seem to mind. After all, fat is just fat, and fat is delicious.