School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
Indigo Science Ltd., Ashley Down, Bristol, BS7 9JS, United Kingdom.
J Dairy Sci. 2021 Jan;104(1):1087-1098. doi: 10.3168/jds.2020-19024. Epub 2020 Nov 12.
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.
宫颈阴道分泌物是黏蛋白、离子、盐和水的混合物，其比例在生殖周期中发生变化。据推测，这种黏液会发出重要的挥发性信号，表明女性的生殖状态。本研究的目的是鉴定牛宫颈阴道分泌物中的挥发性有机化合物（VOC），这些化合物在发情周期中发生变化，可能可作为发情和排卵的生物标志物。从杂交肉牛小母牛（n=8）中收集宫颈阴道分泌物，这些小母牛使用 8 天的控制内部药物释放（CIDR）方案同步，并通过肉眼观察和超声检查分别确定发情开始和排卵时间。在 CIDR 去除后 0 至 96 小时内收集黏液样本（CIDR 去除后 49.1±3.3 小时发情开始）。在一个独立的 15 头小母牛组中进行了验证研究，在 CIDR 去除后 40 至 80 小时内每 8 小时采集一次宫颈阴道分泌物样本。使用气相色谱-质谱法鉴定黏液中的 VOC，并使用选择离子流管质谱法对选定的化合物进行定量。气相色谱-质谱法检测到黏液样本中存在 47 种 VOC，其中丰度最高的包括 2-丁酮、丙酮、2-戊酮、4-甲基-2-戊酮、1-（1-甲氧基）-2-丙酮、乙醇、2-甲基-2-丙醇和 2-丁醇。所有 VOC 均在发情开始后 24 至 47 小时达到峰值（排卵发生在发情开始后 26.6±5.6 小时）。两种 VOC，2-戊酮和 4-甲基-2-戊酮，在发情开始时显著增加，而 2-丁酮的浓度在发情开始后显著增加，表明这些 VOC 可能可用作发情的推定生物标志物。本研究结果可能有助于开发基于 VOC 的传感器设备，以辅助牛发情和排卵的检测，特别是在大多数母牛通过人工授精繁殖的奶牛业中具有重要意义。
