Laboratory of Chemical and Behavioural Ecology, Institute of Ecology, Nature Research Centre, LT-08412 Vilnius, Lithuania; Ecological Chemistry Group, Division of Organic Chemistry, Department of Chemistry, School of Chemistry and Engineering, Royal Institute of Technology, SE-10044 Stockholm, Sweden.
Institute of Animal Science, Lithuanian University of Health Sciences, LT-82317 Baisogala, Lithuania.
J Dairy Sci. 2017 Sep;100(9):7686-7695. doi: 10.3168/jds.2016-12376. Epub 2017 Jun 28.
Determination of the optimal insemination time in dairy cows is vital for fertilization success and is a challenging task due to silent or weak signs of estrus shown by some cows. This can be overcome by combining several estrus detection methods, leading to higher detection rates. However, an efficient, noninvasive method for detecting estrus in cows is still needed. Chemical cues released by the cow during estrus have been proposed to have pheromonal properties and signal readiness to mate to the bull. Such cues could be used in an industrial setting to detect cows in estrus. However, no conclusive published data show temporal changes in putative sex pheromone levels during estrus. The goal of this study was to determine the temporal pattern of putative sex pheromone components during estrus and to assess the reproducibility of changes in pheromone concentration with respect to ovulation time. Two injections of the hormone PGF were administered over a 2-wk interval to induce and synchronize the estrous cycles of 6 Holstein cows. The precise time of ovulation was determined by means of an ultrasound technique, and estrus was determined by visual observation. Using solid-phase microextraction gas chromatography-mass spectrometry techniques, we showed that acetic and propionic acids, which have been proposed to be putative sex pheromone components in cows, were present in the headspaces of all estrous and diestrous fecal samples, whereas 1-iodoundecane was not detected by solid-phase microextraction or by solvent extraction with diethyl ether. Low levels of acids were observed until 1 d before ovulation, at which point their concentrations increased, peaking around 0.5 d before ovulation. The application of labeled synthetic standards revealed that during the peak of release, 36 ± 8 ng (average ± SD) of acetic acid and 10 ± 3 ng of propionic acid were present in 0.5-g samples of estrous-phase fecal matter compared with 19 ± 5 and 2.3 ± 1 ng of acetic and propionic acids, respectively, in the control diestrous samples. After the peak, the amounts of the compounds decreased sharply to match those of the control samples and afterward returned to the baseline readings. This decrease in the amounts of putative pheromone components was registered about 12 h before ovulation, indicating that acetic and propionic acids could be used as biomarkers for the electronic detection of ovulation.
确定奶牛的最佳授精时间对于受精成功至关重要，但由于一些奶牛表现出安静或微弱的发情迹象，这是一项具有挑战性的任务。通过结合几种发情检测方法可以克服这个问题，从而提高检测率。然而，仍然需要一种高效、非侵入性的奶牛发情检测方法。有研究提出，奶牛在发情期间释放的化学线索具有信息素特性，并向公牛发出交配准备就绪的信号。这些线索可以在工业环境中用于检测发情的奶牛。然而，目前还没有确凿的已发表数据表明发情期间所谓的性信息素水平存在时间变化。本研究的目的是确定发情期间所谓性信息素成分的时间模式，并评估发情期间信息素浓度变化与排卵时间的重现性。通过 2 周的时间间隔给 6 头荷斯坦奶牛注射激素 PGF，以诱导和同步发情周期。通过超声技术确定排卵的确切时间，并通过视觉观察确定发情时间。我们使用固相微萃取气相色谱-质谱技术表明，已被提议为奶牛的所谓性信息素成分的乙酸和丙酸存在于所有发情和间情期粪便样品的顶空部分，而 1-碘十一烷则未通过固相微萃取或二乙醚溶剂萃取检测到。在排卵前 1 天之前，这些酸的浓度一直较低，此时它们的浓度开始增加，在排卵前 0.5 天左右达到峰值。应用标记的合成标准品表明，在释放高峰期，发情期粪便样品中 0.5 克样品中存在 36±8ng（平均值±标准差）的乙酸和 10±3ng 的丙酸，而对照间情期样品中分别存在 19±5ng 和 2.3±1ng 的乙酸和丙酸。峰值过后，这些化合物的含量急剧下降，与对照样品的含量相匹配，之后又恢复到基线读数。这些所谓的信息素成分含量的减少大约在排卵前 12 小时被记录下来，这表明乙酸和丙酸可以作为排卵电子检测的生物标志物。
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