2006 Annual Report 4d.Progress report. This report serves to document research conducted under Non-funded Cooperative Agreement #58-5442-5-0108N between ARS and Virginia Poly Institute and State University. Additional details of research can be found in the report for the parent project 5442-32000-010-00D, Prevent the Occurrence of Toxins in Water to Protect Food and the Environment. A trial to investigate antibiotic and coccidiostat residues in poultry litter was completed. A bio-assay for detection of antibiotic activity was developed. While bacitracin standards reproducibly resulted in bacterial inhibition, antibiotic activity was not found in extracts from clean litter spiked with bacitracin. Preliminary results by ELISA corroborated results from bio-assay. When concentrated two-fold, water extracts of clean (unused) litter were found to have antibiotic activity (against the test organism, Bacillus megaterium). Early findings using poultry litter from bacitracin-treated birds indicate a lack of water extractable antibacterial activity; therefore, field application of litter from these birds may not have antibacterial significance.