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Spring 1993

Research Magazine > ARCHIVE > Spring 93 > Article

From Trash to Trough
New Technique Turns Farm Waste Into Animal Feed
by Phil Williams

A new salvage technique may help rescue the environment down on the farm.

When poultry and livestock die, farmers must get rid of them quickly. But cleaning out the hen house is becoming more and more of an environmental headache. Each year 150 million pounds of dead chickens end up in the garbage of Georgia poultry producers.

Trashing dead chickens and other farm animals -- either by burying or burning them -- is the time-honored disposal method. Another infrequently used option -- taking them to rendering plants -- is usually deemed too expensive.

But faced with concerns over groundwater and air pollution, farmers are looking for safer, cleaner disposal methods.

Dr. Jean Sander has found one.

The research veterinarian developed a technique that not only eliminates the environmental problems of disposal but also converts carcasses into something useful: a protein source for livestock feed.

Sander's recipe for salvaging carcasses involves grinding them and then letting bacteria go to work to break down the animal tissue. She "feeds" the bacteria with a carbohydrate source, much like wine makers add sugar to yeast to produce wine. Sander then stores the bacteria-rich mixture in the absence of oxygen for seven days, but instead of wine, bacteria produce a protein that can be used to make nutritious animal feed.

Although farmers probably won't make a killing on the carcass mixture -- it has a modest cash value -- eventually they may save on their disposal costs. And the process definitely will save space in the landfill.

Building on the work of her colleagues in the College of Veterinary Medicine, Sander found that useful bacteria already were present and could be "encouraged" to grow when whey, cornmeal or molasses was added.

These bacteria produce lactic acid and that makes the ground carcasses less likely to spoil, Sander said. The process also removes all but typical farm odors from the product.

"The real issue is stabilizing whatever product we find," she said. "So far, this system is doing a good job of that. Research by others has shown that in seven days, this process kills virtually all bacteria and viruses."

Sander and her colleagues have started a pilot operation at Crystal Farms in Braselton, Ga. in which chicken carcasses are ground in a machine she compares to a "chipper-shredder." Currently the process is yielding about 14 tons of ground material each month.

Although the cost of a machine -- about $4,000 -- may be a drawback to some meat producers, Sander said changes in the laws may make such alternative disposal methods mandatory. Some states already restrict incineration and pit burial for carcasses, she said.

While the technology for storing and transporting the ground carcasses is close to completion, questions still remain.

"We need to know about anything that affects the end product as a source for nutrition," she said. "This can help us ensure that livestock receive nutritionally balanced feed."

Sander said she plans to study biochemical changes in the process, such as alterations in the structure and content of fatty acids or amino acids. She said she also wants to expand the process to include other farm and laboratory animals.

In the meantime, Sander continues to refine the pilot process. And though her technique won't change life down on the farm, it will reduce the number of animals that end up at the landfill.

Research Communications, Office of the VP for Research, UGA
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