Submitted to: Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2016
Publication Date: 5/14/2016
Publication URL: http://handle.nal.usda.gov/10113/62633
Citation: Arikan, O., Mulbry III, W.W., Rice, C. 2016. The effect of composting on the persistence of four ionophores in dairy manure and poultry litter. Waste Management. 54:110-117.
Interpretive Summary: Ionophore compounds are commonly used in livestock production to control coccidiosis (an intestinal disease caused by parasites), as well as for promoting faster growth of the animals. Ionophores are toxic to human cells and are therefore not used except for veterinary purposes. Since ionophores aren’t used in humans, land application of ionophore-containing manure does not pose a potential threat to public health by influencing the development of antibiotic resistance in human pathogens. However, these compounds inhibit the activity of many bacteria and eukaryotic cells and can affect soil invertebrates and aquatic organisms. Although reported half-lives for these compounds in soils are very short (typically 2-4 days), ionophores have been detected in surface water and groundwater. Treatment of ionophore-containing manure prior to land application, is one possible means of reducing the amount of these compounds that is released into the environment. The specific objective of this study was to determine the relative effectiveness of composting temperatures to reduce the concentrations of four widely used ionophores (monensin, lasalocid, amprolium and salinomycin). Laboratory-scale incubations were conducted using both dairy manure and poultry litter to determine the influence of the composting matrix on removal rates. Results showed that of the four ionophores tested in dairy manure, only salinomycin was removed more quickly at composting temperatures relative to ambient temperature. In poultry litter, the highest composting temperature (65 C) increased the removal rates of two of the four ionophores (lasalocid and amprolium), relative to the ambient temperature treatment. However, amprolium rates may be too slow to be useful in practice (8-12 weeks at 65 C for >90% residue removal). Results from this study compliments those from previous studies, and allows for practical decisions of whether composting efforts are likely to reduce specific ionophore levels below those in unmanaged manure or poultry stockpiles. These results will be useful for scientists and agencies interested in the environmental fate of feed additives, the composting industry, and dairy and poultry producers.
Technical Abstract: Manure composting is a well-described approach for stabilization of nutrients and reduction of pathogens and odors. Although composting studies have shown that thermophilic temperatures and aerobic conditions can increase removal rates of selected antibiotics, comparable information is lacking for many other compounds in untreated or composted manure. The objective of this research was to determine the relative effectiveness of composting conditions to reduce concentrations of four widely used ionophore feed supplements in dairy manure and poultry litter. Replicate aliquots of fresh poultry litter and dairy manure were amended with monensin, lasalocid, amprolium, or salinomycin to 10mg per kilogram and incubated at 22, 45, 55, or 65 C under moist, aerobic conditions. Residue concentrations were determined from aliquots removed after 1, 2, 4, 6, 8, and 12 weeks. Results suggest that the effectiveness of composting for contaminant reduction is compound and matrix specific. Composting temperatures were not any more effective than ambient temperature in increasing the rate or extent of monensin removal in either poultry litter or dairy manure. Composting was effective for lasalocid removal in poultry litter, but is likely to be too slow to be useful in practice (8-12 weeks at 65 C for >90% residue removal). Composting was effective for amprolium removal from poultry litter and salinomycin in dairy manure but both required 4-6 weeks for >90% removal. However, composting did not increase the removal rates of salinomycin in poultry litter or the removal rates of lasalocid or amprolium in dairy manure.