title: GC analysis of essential oils in the rumen fluid after incubation of Thuja orientalis twigs in the Rusitec system.
abstract: Methods for the chemical analysis of toxic plant substances in the rumen of ruminants are of importance for the diagnosis of intoxications with poisonous plants. The present work establishes a method to estimate monoterpene components of the essential oil of thuja (Thuja orientalis, Cupressaceae) in these types of samples. Alpha-thujone, which is regarded as the toxic principle, is present at a concentration of 50-60% in the essential oil. The rumen simulation technique (Rusitec) was used to simulate natural digestion. Chopped twigs of thuja were subjected to rumen content in a closed container with an overflow device. The flow of saliva was simulated by the continuous addition of a buffer solution. Samples for analysis were taken from the overflow at 24 and 48 h. A further sample was taken from the remaining liquid fraction of the rumen content in the container at 48 h. The essential oils were extracted with hexane and concentrated. A quantitative determination was done by capillary gas chromatography. Together in the three fractions analysed this resulted in total mean recoveries of 6.8% for alpha-thujone, 5.3% for beta-thujone, 18.9% for fenchone and 27.8% for camphor. The observation that the thujones were recovered to a lesser extent than other oil components is evidence of their fast decomposition in the rumen medium. Under these circumstances the calculated detection limit is 100-200 g thuja twigs in cows with rumen volumes of 60-100 litres. The main essential oil degradation products found in the rumen fluid of all three fractions in the Rusitec system were discovered to be iso-3-thujanol, neo-3-thujanol, carvomenthol and carvomenthone.
authors.affiliation: Institute for Applied Botany, University of Veterinary Medicine, Vienna 1210, Austria. remigius.chizzola@vu-wien.ac.at
authors.forename: R
authors.initials: R
authors.lastname: Chizzola
authors.forename: W
authors.initials: W
authors.lastname: Hochsteiner
authors.forename: S
authors.initials: S
authors.lastname: Hajek
mesh_terms: D000818:Animals; D002417:Cattle; D002849:Chromatography, Gas; D004063:Digestion; D008401:Gas Chromatography-Mass Spectrometry; D008954:Models, Biological; D009822:Oils, Volatile / Q000032:analysis* / Q000493:pharmacokinetics*; D018547:Plant Stems / Q000737:chemistry*; D010947:Plants, Toxic; D012417:Rumen / Q000737:chemistry* / Q000378:metabolism*; D029783:Thuja / Q000737:chemistry*
chemical_list: D009822:Oils, Volatile