|ARIKAN, OSMAN - Istanbul Technical University|
|LANSING, STEPHANIE - University Of Maryland|
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2018
Publication Date: 2/21/2018
Publication URL: http://handle.nal.usda.gov/10113/5934965
Citation: Arikan, O., Mulbry III, W.W., Rice, C., Lansing, S. 2018. The fate and effect of monensin during anaerobic digestion of dairy manure under mesophilic conditions. PLoS One. 13(2):e0192080. https://doi.org/10.1371/journal.pone.0192080
Interpretive Summary: Raw manure can be a significant source of antibiotics and other pharmaceutically active compounds (PACs). When animal producers remove manure from pens, housing units, barns or sheds, the manure is stockpiled until time and circumstances are available to land apply the material. To the extent that manure stockpiles contain antibiotics and PACs, this land-applied material will contribute to the contamination of soil and water and to the development of antibiotic resistance among native microbial communities. Therefore, it is important to implement appropriate management practices that minimize the risk of disseminating antibiotics and PACs from the stockpiled manure. The objective of this study was to determine the fate and effect of the widely used compound monensin during the anaerobic digestion of dairy manure. Results from replicate field scale digesters showed that 50 to 70% of the monesin added to the digesters was not degraded. Thus, anaerobic digestion is not an effective method for reducing monensin levels in animal manure. Results also showed that, at levels typically found in dairy manure, monensin does not have a significant effect on methane production. These results could be useful for animal producers and the anaerobic digestion industry who are interested in the use of animal manure for biogas production.
Technical Abstract: There is growing concern about environmental impact of residual antibiotics and feed additives in the manure of treated animals. Monensin, a polyether ionophore coccidiostat, is the only feed additive permitted for use in the U.S. for lactating dairy cows. Previous research has shown that up to 50% of the monensin administered to cattle is excreted in the manure. Anaerobic digestion is an established technology for animal manure and can be affected by monensin residues. The objective of this study was to determine the fate and effect of monensin during the anaerobic digestion of dairy manure. Duplicate plug flow field-scale digesters were operated using dairy manure and dairy manure amended with monensin to 1 and 10 mg per liter. Digesters were operated for 8 weeks at 30 C, an organic loading rate of 1.4 kg VS per cubic meter-day, and a 17-day hydraulic retention time. Results show that mean effluent monensin concentrations were 0.5 ± 0.1 mg per liter and 3.3 ± 1.1 mg per liter from the digesters amended with 1 and 10 mg per liter monensin, respectively. Approximately 20% of influent monensin was associated with solids that settled in the digesters. Digesters operated with manure containing 1 and 10 mg per liter monensin produced 12% and 75% less methane, respectively, compared to digesters operated without monensin. These results suggest that anaerobic digestion is not an effective treatment for removing monensin in dairy manure. In dairy manure at concentrations less than 1 mg per liter, monensin does not have significant effect on biogas production.