2008 Annual Report 1a.Objectives (from AD-416) Develop and evaluate lab and farm-scale manure treatment methods to remove oxytetracycline and chlorotetracycline residues; Evaluate different agricultural and industrial by-products for co-digestion with animal manures for bioenergy production and antibiotic reduction. 1b.Approach (from AD-416) Chlortetracycline and oxytetracycline are broad-spectrum antibiotics used for prophylactic and therapeutic use in poultry, pigs, and cows. Results from laboratory-scale studies demonstrate that these compounds are rapidly degraded during composting of dairy manure-straw-woodchip mixtures. However, further research is necessary to properly evaluate this treatment method at the lab and farm scale with different types of animal wastes. In this research, engineering parameters for lab and farm-scale manure treatment systems will be developed and used to conduct antibiotic removal experiments. Although small dairy farms do not generate enough manure for electrical production from biogas, there are significant opportunities to combine other byproducts with the manure to significantly increase biogas production. Initial experiments using lab-scale reactors will be used to characterize biogas production and reactor parameters during co-digestion of dairy manure or poultry litter with a variety of organic by-products. Subsequent co-digestion experiments at pilot-scale will focus on a select group of by-products. 3.Progress Report Determined the fate of the antibiotic chlorotetracycline (CTC) during composting of manure from treated beef calves. The use of antibiotics as growth promoters and therapeutic agents is widespread in the animal production industry. However, there is a growing concern about the potential impact of antibiotic residues from such agricultural sources on the development of antibiotic-resistant bacteria. Previous studies have shown that between 17-76% of antibiotics administered to animals are excreted via urine and feces in unaltered form and as metabolites. Land application of manure as a supplement to fertilizer is a common practice in many countries. It is therefore likely that when animal manure applied to a land, antibiotic residues can find their way into the receiving environment. Chlortetracycline (CTC) is an antibiotic used in livestock production that is active against a wide range of gram-positive and gram-negative bacteria. Treatment of manure containing CTC is one possible means of reducing the amount of this compound that is ultimately released into the environment. Manure composting is a well-described approach for stabilization of nutrients and reduction of pathogens and odors. In addition, composting has been shown to be effective in reducing relatively persistent organic compounds such as pharmaceuticals and personal care products. The objective of this study was to determine the effect of composting on CTC residues in manure from medicated calves. Results from laboratory scale composting experiments showed that concentrations of CTC and its metabolites decreased more than 99% in 30 days in manure/straw/woodchip mixtures that reached normal composting temperatures (55 C). In comparison, concentrations of CTC and its metabolites decreased about 40% in 30 days in manure/straw/woodchip mixtures that were incubated at room temperature (25 C). Results from experiments using sterilized manure/straw/woodchip mixtures showed that the decreases in CTC concentrations at 25 C and 55 C were largely due to non-biological processes such as adsorption to organic material rather than to degradation by microorganisms. ADODR monitoring was accomplished by telephone conference and by email.