In response to a December federal ban on allowing sick or otherwise debilitated animals from entering the food market, farmers across the country are struggling with how to deal with these so called “downer” cattle.
Secretary of Agriculture Ann Veneman said the new policy will “ban all downer cattle from the human food chain.” The ban is part of an attempt by the Bush administration to restore domestic and international confidence in the beef industry after it was rocked by the detection of mad cow disease, bovine spongiform encephalopathy, in a Washington state cow.
Researchers at the Cornell Waste Management Institute have been testing a both environmental and economically efficient technique that will help deal with the over 150,000 cows affected annually by the ruling. The process, known as natural rendering, involves composting the entire steer in a pile similar to vegetable and trash compost heaps in backyards across the country.
“Put a 24 inch layer woodchips on the bottom then the animal will go in there, then cover it with a layer of sawdust” described Jean Bonhotal, a researcher at the waste institute. “In the first month it pretty much looks like cooked meat, the microorganisms dine on things, and by the third month you pretty much have clean bones.” The waste institute produced a video and pamphlet that describes the process in detail for farmers and other potential users. During decomposition, the action of microbes drives temperature up to 160 degrees Fahrenheit, which effectively kills most pathogens in the compost pile. The method takes under six months to reduce a 1200 pound steer to bare bones.
Although farmers have used composting to deal with chickens and pigs for quite some time, Cornell’s application to sick cattle “caught on because the time is right,” said Bonhotal. “With the downer cow ban there are more animals that have to be dealt with.”
Decreased demand for carcass products such as hides and bonemeal have driven up the price of sending downer cattle to rendering plants. The traditional solution to dealing with sick animals and the roughly 700 pounds of unusable slaughter byproducts from each steer.
Soaring costs have driven some farmers to simply drag dead animals to a remote part of their property and leave them unexposed or buried in shallow pits to be dealt with by scavengers and decomposition. This quick-fix simultaneously poses a contamination threat to other cattle on the farm and endangers the nearby human water supply.
According to the waste institute, New York state’s livestock producers stand to save over half a million dollars by employing natural rendering. In addition to providing a cheap, simple, and biologically safe solution to the problem of downer cattle, natural rendering creates compost rich in plant nutrients such as potassium, nitrogen and phosphorus. Contrasting other, more expensive disposal techniques, the new method can be implemented any time of year, is relatively odor free, and can be used with any sized animal.
The boundaries of his process were tested by researchers at the Paleontological Research Institute when they trucked to the outskirts of Ithaca a right-whale that died off the coast of New Jersey. After being covered with a thick blanket of horse manure, the 300,000 pound creature took only 12 months to completely decompose. The researchers then returned to recover the bones and reassemble the skeleton for display.
Despite its potential to deal with mass amounts of biological waste, natural rendering does have its limitations. According to Ellen Harrison, the director of the waste institute, it cannot be used to safely dispose of animals that have Mad Cow disease. “Although composting reaches high enough temperatures for a long enough time to kill most pathogens,” said Harrison, “it would be highly unlikely that composting would inactivate prions.” Prions are the tiny proteins responsible for transmitting the disease from one animal to another.
Harrison adds that the waste institute is extending the function of natural rendering beyond use on farms to dealing with roadkill.
“We hope to help local highway departments,” she said. “Right now they pay significant chunk of cash for a contractor to get rid of deer.”
Highway departments applying the natural rendering technique could save local taxpayers thousands of dollars.
Archived article by Neil Mukhopadhyay