Research Magazine > ARCHIVE > Spring
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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
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
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
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.
Communications, Office of the VP for Research, UGA
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