Swine Odor Analyzed by Odor Panels and Chemical Techniques
- Steven Trabue ,
- Brian Kerr,
- Bradley Bearson and
- Cherie Ziemer
- USDA–ARS, National Laboratory for Agriculture and the Environment, 2110 University Blvd., Ames, IA 50011. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and use of the name by the USDA implies no approval of the product to the exclusion of others that may be suitable. Assigned to Associate Editor Sean McGinn
The National Research Council identified odors as a significant animal emission and highlighted the need to develop standardized protocols for sampling and analysis. The purpose of our study was to compare different odor sampling techniques for monitoring odors emitted from stored swine manure. In our study, odorous headspace air from swine manure holding tanks were analyzed by human panels and analytical techniques. Odorous air was analyzed by human panels using dynamic dilution olfactometry (DDO). Chemical analysis used acid traps for ammonia (NH3), fluorescence for hydrogen sulfide (H2S), and thermal desorption gas chromatography–mass spectrometry for volatile organic compounds (VOCs). Chemical analysis included the use of gas chromatography–olfactometry (GC-O) for determining key odorants. Chemical odorant concentrations were converted to odor activity values (OAVs) based on literature odor thresholds. The GC-O technique used was GC-SNIF. Dilution thresholds measured by different odor panels were significantly different by almost an order of magnitude even though the main odorous compound concentrations had not changed significantly. Only 5% of the key odorous VOCs total OAVs was recovered from the Tedlar bags used in DDO analysis. Ammonia was the only chemical odorant significantly correlated with DDO analysis in the fresh (1 wk) and aged manure. Chemical analysis showed that odor concentration stabilized after 5 to 7 wk and that H2S was the most dominant odorant. In aged manure, neither volatile fatty acids (VFAs) nor H2S was correlated with any other chemical odorant, but NH3, phenols, and indoles were correlated, and phenols and indoles were highly correlated. Correlation of odorant concentration was closely associated with the origin of the odorant in the diet. Key odorants determined by chemical and GC-O included indoles, phenols, NH3, and several VFAs (butanoic, 3-methylbutanoic, and pentanoic acids).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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