Freising, Germany
Freising, Germany

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Demmel M.,Institute for Agricultural Engineering and Animal Husbandry | Brandhuber R.,Institute for Agroecology | Kirchmeier H.,Institute for Agricultural Engineering and Animal Husbandry | Muller M.,Institute for Agricultural Engineering and Animal Husbandry | Marx M.,Institute for Agroecology
Landtechnik | Year: 2012

Controlled traffic farming (CTF) systems have been installed and investigated on three arable farms in Bavaria. Particularly the technical realization, the advantages of different systems and the effect on soil water should be examined. The farm equipment used meet German traffic regulations. Hence, the portion of non-trafficked land is limited to 58-67 %. RTK DGPS based automatic steering systems were used for all field work. Already in the second year of the experiment a tendency to increased water availability was observed in the non-trafficked areas. Crop yields did not show unidirectional reactions in the seasons of 2010 and 2011. Because long dry periods in the main seasons did not occur the expected advantages of controlled traffic farming could not be confirmed.

Holzel C.S.,TU Munich | Schwaiger K.,TU Munich | Harms K.,TU Munich | Kuchenhoff H.,Ludwig Maximilians University of Munich | And 4 more authors.
Environmental Research | Year: 2010

Within the last decades, the environmental spread of antibiotic resistant bacteria has become a topic of concern. In this study, liquid pig manure (n=305) and sewage sludge (n=111) - used as agricultural fertilizers between 2002 and 2005 - were investigated for the presence of Escherichia coli, Enterococcus faecalis and Enterococcus faecium. Bacteria were tested for their resistance against 40 chemotherapeutics including several "reserve drugs". E. coli (n=613) from pig manure were at a significantly higher degree resistant to streptomycin, doxycycline, spectinomycin, cotrimoxazole, and chloramphenicol than E. coli (n=116) from sewage sludge. Enterococci (Ent. faecalis, n=387, and Ent. faecium, n=183) from pig manure were significantly more often resistant to high levels of doxycycline, rifampicin, erythromycin, and streptomycin than Ent. faecalis (n=44) and Ent. faecium (n=125) from sewage sludge. Significant differences in enterococcal resistance were also seen for tylosin, chloramphenicol, gentamicin high level, fosfomycin, clindamicin, enrofloxacin, moxifloxacin, nitrofurantoin, and quinupristin/dalfopristin. By contrast, aminopenicillins were more effective in enterococci from pig manure, and mean MIC-values of piperacillin+tazobactam and third generation cefalosporines were significantly lower in E. coli from pig manure than in E. coli from sewage sludge. 13.4% (E. coli) to 25.3% (Ent. faecium) of pig manure isolates were high-level multiresistant to substances from more than three different classes of antimicrobial agents. In sewage sludge, high-level-multiresistance reached from 0% (Ent. faecalis) to 16% (Ent. faecium). High rates of (multi-) resistant bacteria in pig manure emphasize the need for a prudent - cautious - use of antibiotics in farm animals. © 2010 Elsevier Inc. All rights reserved.

Holzel C.S.,TU Munich | Harms K.S.,TU Munich | Kuchenhoff H.,Ludwig Maximilians University of Munich | Kunz A.,Ludwig Maximilians University of Munich | And 4 more authors.
Journal of Applied Microbiology | Year: 2010

Aims: Antibiotic residues as well as antibiotic-resistant bacteria in environmental samples might pose a risk to human health. This study aimed to investigate the association between antibiotic residues and bacterial antimicrobial resistance in liquid pig manure used as fertilizer. Methods and Results: Concentrations of tetracyclines (TETs) and sulfonamides (SULs) were determined by liquid chromatography-mass spectrometry in 305 pig manure samples; antibiotic contents were correlated to the phenotypic resistance of Escherichia coli (n = 613) and enterococci (n = 564) towards up to 24 antibiotics. In 121 samples, the concentration of the TET resistance genes tet(M), tet(O) and tet(B) was quantified by real-time-PCR. TETs were found in 54% of the samples. The median sum concentration of all investigated TETs in the positive samples was 0·73 mg kg-1. SULs were found with a similar frequency (51%) and a median sum concentration of 0·15 mg kg-1 in the positive samples. Associated with the detection of TETs and/or SULs, resistance rates were significantly elevated for several substances - some of them not used in farm animals, e.g. chloramphenicol and synercid. In addition, multiresistant isolates were found more often in samples containing antibiotics. Analysis of the resistance genes tet(M) and tet(O) already showed a significant increase in their concentrations - but not in tet(B) - in the lowest range of total TET concentration. Mean tet(M) concentrations increased by the factor of 4·5 in the TET concentration range of 0·1-1 mg kg-1, compared to negative manure samples. Conclusions: Antibiotic contamination of manure seems to be associated with a variety of changes in bacterial resistance, calling for a prudent use of antibiotics in farm animals. Significance and Impact of the Study: This study provides an interdisciplinary approach to assess antimicrobial resistance by combining the microbiological analysis of bacterial resistance with high quality chemical analysis of antibiotic residues in a representative number of environmental samples. © 2009 The Society for Applied Microbiology.

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