ARS scientists have found composting beef manure
can significantly reduce antibiotics and pathogens. Photo courtesy of
Natural Resources Conservation Service.
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Minimal Composting of Beef Cattle Manure Reduces
Antibiotic Levels
By Sharon
Durham
September 22, 2008 Composting beef cattle manure,
even with minimal management, can significantly reduce the concentrations of
antibiotics in the manure, according to an Agricultural Research Service (ARS) pilot
study. The scientists found that composting manure from beef cattle could
reduce concentrations of antibiotics by more than 99 percent.
Osman Arikan, a visiting scientist from Istanbul Technical University, and ARS
microbiologists
Patricia
Millner and
Walter
Mulbry at the
Henry
A. Wallace Beltsville Agricultural Research Center, in Beltsville, Md.,
looked at varying levels of manure management, including plain manure piles,
and manure piles with straw added. They found that adding straw to manure piles
tends to result in higher temperatures that speed up the process of degrading
antibiotics as well as pathogens.
The use of antibiotics as therapeutic agents is widespread in the animal
production industry. Scientific studies have shown that, depending on the
antibiotic and type of animal, between 20 to 75 percent of antibiotics
administered to animals is excreted via urine and feces. So it's important that
these residues are broken down during composting to prevent their release into
the environment.
Arikan, Millner, and Mulbry evaluated the efficacy of a series of
minimal-management options for on-farm manure composting to reduce
concentrations of the antibiotics oxytetracycline and chlorotetracycline. The
treatments were designed to span a range of management options from simply
piling up the manure to mixing it with an equal volume of straw (to increase
aeration within the compost pile) and adding insulating layers of straw.
Results show that manure-only pile temperatures and the concentrations of
antibiotics were significantly influenced by treatment over a 28-day period.
Concentrations of oxytetracycline and chlorotetracycline incubated at ambient
temperature decreased 75 percent and 90 percent, respectively.
Oxytetracycline and chlorotetracycline concentrations in samples incubated
for 28 days within an amended manure pile decreased 91 percent and 99 percent,
respectively. Although manure piles amended with straw attained higher
temperatures and more rapid decreases in antibiotic concentrations, there is
currently no compelling justification for producers to expend additional
resources needed to achieve the more rapid rates of antibiotic removal.
Pathogen reduction in manure piles requires careful and consistent management
to ensure all parts of the pile are treated.
ARS is a scientific research agency in the U.S. Department of Agriculture.