Rørvang Maria Vilain, Nicova Klára, Yngvesson Jenny
Department Biosystems and Technology, Swedish University of Agricultural Sciences, Lomma, Sweden.
Department of Ethology, Institute of Animal Science, Prague, Czechia.
Front Behav Neurosci. 2022 Jul 28;16:941517. doi: 10.3389/fnbeh.2022.941517. eCollection 2022.
In spite of a highly developed olfactory apparatus of horses, implying a high adaptive value, research on equine olfaction is sparse. Our limited knowledge on equine olfaction poses a risk that horse behavior does not match human expectations, as horses might react fearful when exposed to certain odors, which humans do not consider as frightening. The benefit of acquiring more knowledge of equine olfaction is therefore twofold; (1) it can aid the understanding of horse behavior and hence reduce the risk of dangerous situations, and (2) there may be unexplored potential of using odors in several practical situations where humans interact with horses. This study investigated behavior and olfactory sensitivity of 35 Icelandic horses who were presented with four odors: peppermint, orange, lavender and cedar wood in a Habituation/Dishabituation paradigm. The response variables were sniffing duration per presentation and behavioral reaction (licking, biting, snorting, and backing), and data were analyzed for potential effects of age, sex and pregnancy. Results showed that habituation occurred between successive odor presentations (1st vs. 2nd and 2nd vs. 3rd presentations: < 0.001), and dishabituation occurred when a new odor was presented (1st vs. 3rd presentations: < 0.001). Horses were thus able to detect and distinguish between all four odors, but expressed significantly longer sniffing duration when exposed to peppermint (peppermint vs. orange, lavender and cedar wood: < 0.001). More horses expressed licking when presented to peppermint compared to cedar wood and lavender ( = 0.0068). Pregnant mares sniffed odors less than non-pregnant mares ( = 0.030), young horses (age 0-5 years) sniffed cedar wood for longer than old horses ( = 0.030), whereas sex had no effect ( > 0.050). The results show that horses' odor exploration behavior and interest in odors varies with age and pregnancy and that horses naïve to the taste of a substrate, may be able to link smell with taste, which has not been described before. These results can aid our understanding of horses' behavioral reactions to odors, and in the future, it may be possible to relate these to the physiology and health of horses.
尽管马拥有高度发达的嗅觉器官，这意味着其具有很高的适应性价值，但对马嗅觉的研究却很稀少。我们对马嗅觉的有限了解带来了一种风险，即马的行为可能不符合人类的期望，因为当马接触到某些人类并不认为可怕的气味时，它们可能会表现出恐惧反应。因此，获取更多马嗅觉知识的益处是双重的；（1）它有助于理解马的行为，从而降低危险情况发生的风险，（2）在人类与马互动的几个实际场景中，使用气味可能存在尚未被探索的潜力。本研究采用习惯化/去习惯化范式，对35匹冰岛马在面对薄荷、橙子、薰衣草和雪松木四种气味时的行为和嗅觉敏感性进行了调查。反应变量为每次呈现时的嗅闻持续时间和行为反应（舔舐、啃咬、喷气和后退），并对年龄、性别和怀孕情况的潜在影响进行了数据分析。结果表明，在连续的气味呈现之间出现了习惯化（第1次与第2次以及第2次与第3次呈现：<0.001），而当呈现新气味时出现了去习惯化（第1次与第3次呈现：<0.001）。因此，马能够检测并区分所有四种气味，但在接触薄荷时表现出显著更长的嗅闻持续时间（薄荷与橙子、薰衣草和雪松木相比：<0.001）。与雪松木和薰衣草相比，更多的马在接触薄荷时表现出舔舐行为（=0.0068）。怀孕母马嗅闻气味的次数少于未怀孕母马（=0.030），幼马（0至5岁）嗅闻雪松木的时间比老马更长（=0.030），而性别没有影响（>0.050）。结果表明，马对气味的探索行为和兴趣随年龄和怀孕情况而变化，并且对某种底物味道不熟悉的马可能能够将气味与味道联系起来，这在以前尚未有过描述。这些结果有助于我们理解马对气味的行为反应，并且在未来，有可能将这些反应与马的生理和健康状况联系起来。
