The potential of volatile organic compound analysis in cervicovaginal mucus to predict estrus and ovulation in estrus-synchronized heifers.

Cervicovaginal mucus is a mixture of mucins, ions, salts, and water, the proportions of which change during the reproductive cycle. It is suspected that this mucus emits an important volatile signal indicative of the reproductive state of the female. The objective of this study was to identify volatile organic compounds (VOC) in bovine cervicovaginal mucus that are modulated during the estrous cycle and could potentially be used as biomarkers of estrus and ovulation. Cervicovaginal mucus was collected from crossbred beef heifers (n = 8), which were synchronized using an 8-d controlled internal drug release (CIDR) protocol and in which onset of estrus and time of ovulation were determined by visual observation and ultrasonography, respectively. Mucus samples were collected between 0 and 96 h after CIDR removal (estrus onset occurred at 49.1 ± 3.3 h after CIDR removal). A validation study was performed on an independent group of 15 heifers from which cervicovaginal mucus samples were collected every 8 h from 40 to 80 h after CIDR removal. The VOC in mucus were identified using gas chromatography-mass spectrometry and selected compounds were quantified using selected-ion flow-tube mass spectrometry. The presence of 47 VOC was detected in mucus samples by gas chromatography-mass spectrometry with those exhibiting highest abundance including 2-butanone, acetone, 2-pentanone, 4-methyl-2-pentanone, 1-(1-methylethoxy)-2-propanone, ethanol, 2-methyl-2-propanol, and 2-butanol. All VOC peaked between 24 to 47 h after the onset of estrus (ovulation occurred 26.6 ± 5.6 h after estrus onset). Two VOC, 2-pentanone and 4-methyl-2-pentanone, exhibited a significant increase at the onset of estrus, whereas concentration of 2-butanone increased significantly just after estrus onset, indicating that these VOC may be used as putative biomarkers of estrus. The results of our study may contribute to the development of a sensor device based on VOC to aid the detection of estrus and ovulation in cattle, with particular relevance for the dairy industry where the majority of females are bred by artificial insemination.

Identification by gas chromatography-mass spectrometry of the volatile organic compounds emitted from the wood-rotting fungi Serpula lacrymans and Coniophora puteana, and from Pinus sylvestris timber.

Volatile organic compounds (VOCs) emitted by two wood-rotting basidiomycete fungi, Serpula lacrymans (dry rot fungus) and Coniophora puteana (cellar fungus), and the timber of Pinus sylvestris (Scots pine), were identified. Several volatile collection techniques were employed including dichloromethane solvent extraction, solid-phase microextraction (SPME) and thermal desorption of VOCs entrained on Tenax GR. In addition, a new method of solid sample injection (SSI) is described which utilises a low injector temperature and an all-glass deactivated injector liner designed to minimise both the formation of pyrolysis products and analyte degradation. All the volatile compounds collected were analysed using electron impact capillary gas chromatography-mass spectrometry (GC-MS) on HP-5, HP-Innowax and beta-cyclodextrin columns. SSI and Tenax thermal desorption were found to be the most effective extraction methods. A total of 19 VOCs were observed from S. lacrymans grown on glass slides and pine, 15 from C. puteana grown on glass slides and 12 from P. sylvestris timber. S. lacrymans was found to emit, in low abundance, six unique VOCs, of which 2-methylbutanal was the greatest. The major volatile compound emitted by S. lacrymans was 1-octen-3-ol, which was also found in lower abundance from C. puteana. Six VOCs, including diethylene glycol and 4-methyl methylbenzoate, were found to be unique to C. puteana, all in medium abundance: From P. sylvestris, the major volatiles identified were S-alpha-pinene and 3-carene.