Application of Solid Phase Microextraction to Compare Emissions of Volatile Organic Compounds from Cattle and Swine Manures.
Daniel Miller, East Campus, USDA-ARS, USDA ARS - U. of Nebraska-Lincoln, 121 Keim Hall, Lincoln, NE 68583-0934 and Bryan L. Woodbury, USDA, ARS, U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933-0166.
Odors from livestock operations are a complex mixture of volatile carbon, sulfur, and nitrogen compounds. Currently, detailed volatiles analysis is both time consuming and requires specialized equipment and methods. This work describes the application of a new method that utilizes a dynamic flux chamber, solid-phase microextraction (SPME), and gas chromatography-mass spectroscopy (GC-MS) to describe and compare the odorous compounds emitted from five cattle and two swine feces. A variety of volatile organic compounds (VOCs) including alcohols, volatile fatty acids, aromatic ring compounds, ketones, esters, and sulfides were routinely detected, with the combined total ion current (TIC) signal varying over a 10-fold range. Aldehydes and esters comprised only a small percentage (< 2.5%) of the TIC in all feces, whereas alcohols, volatile fatty acids, aromatic ring compounds, ketones, esters, and sulfide together accounted for >97.5% of the TIC signal but varied substantially (<1% to >70% of the TIC signal) between feces. Comparing the relative emission of VOC from fresh feces based upon diet formulation, diets high in ground corn emitted more VOC than diets containing high moisture corn or corn silage as principal ingredients. The relative emissions from fresh and incubated (37°C overnight) swine and cattle feces were compared as a measure of the short term potential to produce odor compounds and indicated that diets containing ground corn or high moisture corn had a larger potential for emission after incubation compared to the two corn silage diets.