title: Characterization of volatile organic compounds and odors by in-vivo sampling of beef cattle rumen gas, by solid-phase microextraction, and gas chromatography-mass spectrometry-olfactometry.
abstract: Volatile organic compounds (VOCs) and odors in cattle rumen gas have been characterized by in-vivo headspace sampling by solid-phase microextraction (SPME) and analysis by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). A novel device enabling headspace SPME (HS-SPME) sampling through a cannula was designed, refined, and used to collect rumen gas samples from steers. A Carboxen-polydimethylsiloxane (PDMS) fiber (85 microm) was used for SPME sampling. Fifty VOCs from ten chemical groups were identified in the rumen headspace. The VOCs identified had a wide range of molecular weight (MW) (34 to 184), boiling point (-63.3 to 292 degrees C), vapor pressure (1.05x10(-5) to 1.17x10(2) Pa), and water solubility (0.66 to 1x10(6) mg L-1). Twenty-two of the compounds have a published odor detection thresholds (ODT) of less than 1 ppm. More than half of the compounds identified are reactive and have an estimated atmospheric lifetime of <24 h. The amounts of VFAs, sulfide compounds, phenolic compounds, and skatole, and the odor intensity of VFAs and sulfide compounds in the rumen gas were all higher after feeding than before feeding. These results indicate that rumen gases can be an important potential source of aerial emissions of reactive VOCs and odor. In-vivo sampling by SPME then GC-MS-O analysis can be a useful tool for qualitative characterization of rumen gases, digestion, and its relationship to odor and VOC formation.
authors.affiliation: Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011, USA.
authors.forename: Lingshuang
authors.initials: L
authors.lastname: Cai
authors.forename: Jacek A
authors.initials: JA
authors.lastname: Koziel
authors.forename: Jeremiah
authors.initials: J
authors.lastname: Davis
authors.forename: Yin-Cheung
authors.initials: YC
authors.lastname: Lo
authors.forename: Hongwei
authors.initials: H
authors.lastname: Xin
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D009812:Odorants / Q000032:analysis*; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry*; D012417:Rumen / Q000737:chemistry*; D052617:Solid Phase Microextraction / Q000379:methods*; D014835:Volatilization
chemical_list: D009930:Organic Chemicals