Mares Prefer the Voices of Highly Fertile Stallions

Lemasson, Alban; Remeuf, Kévin; Trabalon, Marie; Cuir, F.; Hausberger, Martine

doi:10.1371/journal.pone.0118468

Cited by 17 publications

(7 citation statements)

References 62 publications

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“…Moreover, particular acoustic parameters of the whinnies have been proposed to encode either the level of arousal or the valence of emotions (e.g. [ 29 , 39 , 40 ]), making acoustic signals highly interesting markers of emotions. Although there is confusion in the terminology associated with non-vocal sounds in horses between studies (snorts, snores, blows being all the consequence of a “forceful exhalation through the nostrils”, the terms have been used interchangeably in many studies), leading to contradictory assumptions about their potential functions, snorts, as defined here (see further) have been mostly associated with a hygienic function of “clearing the nostrils of phlegm, flies or other irritants” [ 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

An unexpected acoustic indicator of positive emotions in horses

Stomp¹,

Leroux²,

Cellier³

et al. 2018

PLoS ONE

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Indicators of positive emotions are still scarce and many proposed behavioural markers have proven ambiguous. Studies established a link between acoustic signals and emitter’s internal state, but few related to positive emotions and still fewer considered non-vocal sounds. One of them, the snort, is shared by several perrisodactyls and has been associated to positive contexts in these species. We hypothesized that this could be also the case in horses. In this species, there is a clear need for a thorough description of non-vocal acoustic signals (snorts, snores or blows are often used interchangeably) but overall this sound produced by nostrils during expiration has up to now been mostly considered as having a hygienic function. However, observations revealed that snorts were produced more in some individuals than in others, without relationship with air conditions. We observed 48 horses living in two “extreme” conditions: restricted conditions (single stall, low roughage diet) and naturalistic conditions (stable groups in pasture). The immediate place (e.g. stall/pasture) and the behavioural/postural (behaviour performed/ears positions) contexts of snort production were observed. We additionally performed an evaluation of the welfare state, using validated behavioural (e.g. stereotypies) and postural (e.g. overall ears positions) welfare indicators. The results show that 1) snort production was significantly associated with situations known to be positive for horses (e.g. feeding in pasture) and with a positive internal state (ears in forward or sidewards positions), 2) the riding school horses produced twice as many snorts when in pasture than in stall, 3) the naturalistic population emitted significantly more snorts than riding school ones in comparable contexts, 4) the frequency of snorts was negatively correlated with the composite total chronic stress score (TCSS, reflecting compromised welfare based on the horse’s rank on the different indicators): the lower the TCSS, the higher the snort rate. Snorts therefore appear as reliable indicators of positive emotions.

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Section: Introductionmentioning

confidence: 99%

An unexpected acoustic indicator of positive emotions in horses

Stomp¹,

Leroux²,

Cellier³

et al. 2018

PLoS ONE

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“…When in breeding season, horses use various sensory cues to assess the reproductive status of their sexual partner such as auditory, visual, or olfactory cues [3][4][5]. In stallions, olfactory communication seems to be one of the mechanisms involved in the assessment of the reproductive status of mares.…”

Section: Introductionmentioning

confidence: 99%

Olfactory stimulation or inhibition of sexual behavior of stallions in non-breeding season

Guillaume

Moussu

Geoffroy

et al. 2018

Physiology & Behavior

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Stallions show decreased sexual responses and activities during short days in winter. To evaluate the importance of sexual olfactory communication in horses, we tested whether sexual responses could be stimulated through various sexual olfactory stimulations in winter. To this end, we presented stallions with various olfactory stimulations (urine from mares at different stages of the reproductive cycle, urine from stallions or geldings, or chemically defined synthetic odorant) during the non-breeding season and measured their behavioral responses through (1) a test of olfactory investigation (olfactory investigation and flehmen behavior) and (2) a test of sexual activity in the context of semen collection for artificial insemination. It appears that the duration of olfactory investigation and flehmen behavior is longer after presentation of urine (stallion, gelding, anestrous, diestrous and estrous mare) than after presentation of water or synthetic odorant. By contrast, geldings showed reduced flehmen behavior that did not differ from that after water presentation. It is of interest that during the mounting test, mare estrous urine was associated with significantly reduced latency to ejaculation when spread in the nostril of the stallion, compared to anestrous mare urine or water. Anestrous mare urine seems to even inhibit stallion sexual motivation as measured through a longer latency to reach mounting and ejaculation. It appears therefore that during the season of sexual rest, stallion sexual motivation can be stimulated by mare estrous urine and inhibited by mare anestrous urine. These results also suggest that the physiological state of the mare influence the content of urinary chemosignals.

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“…Eight call types have been described in this species: whinnies, nickers, squeals, blows, snores, snorts, roars, and groans [ 36 , 37 ]. Whinnies provide information about sex, body size and individuality [ 38 ], reproductive success [ 39 ] and emotions (valence and arousal [ 24 ]), while squeals provide information about dominance status [ 40 ]. Conspecific receivers can decipher familiarity [ 38 , 41 ] and stallion fertility [ 39 ] encoded in whinnies, as well as dominance status encoded in squeals [ 40 ].…”

Section: Introductionmentioning

confidence: 99%

“…Whinnies provide information about sex, body size and individuality [ 38 ], reproductive success [ 39 ] and emotions (valence and arousal [ 24 ]), while squeals provide information about dominance status [ 40 ]. Conspecific receivers can decipher familiarity [ 38 , 41 ] and stallion fertility [ 39 ] encoded in whinnies, as well as dominance status encoded in squeals [ 40 ]. Furthermore, horses are capable of cross-modal individual recognition of conspecifics, matching whinnies to visual/olfactory characteristics of the caller [ 42 ].…”

Section: Introductionmentioning

confidence: 99%

Perception of emotional valence in horse whinnies

et al. 2017

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BackgroundNon-human animals often produce different types of vocalisations in negative and positive contexts (i.e. different valence), similar to humans, in which crying is associated with negative emotions and laughter is associated with positive ones. However, some types of vocalisations (e.g. contact calls, human speech) can be produced in both negative and positive contexts, and changes in valence are only accompanied by slight structural differences. Although such acoustically graded signals associated with opposite valence have been highlighted in some species, it is not known if conspecifics discriminate them, and if contagion of emotional valence occurs as a result. We tested whether domestic horses perceive, and are affected by, the emotional valence of whinnies produced by both familiar and unfamiliar conspecifics. We measured physiological and behavioural reactions to whinnies recorded during emotionally negative (social separation) and positive (social reunion) situations.ResultsWe show that horses perceive acoustic cues to both valence and familiarity present in whinnies. They reacted differently (respiration rate, head movements, height of the head and latency to respond) to separation and reunion whinnies when produced by familiar, but not unfamiliar individuals. They were also more emotionally aroused (shorter inter-pulse intervals and higher locomotion) when hearing unfamiliar compared to familiar whinnies. In addition, the acoustic parameters of separation and reunion whinnies affected the physiology and behaviour of conspecifics in a continuous way. However, we did not find clear evidence for contagion of emotional valence.ConclusionsHorses are thus able to perceive changes linked to emotional valence within a given vocalisation type, similar to perception of affective prosody in humans. Whinnies produced in either separation or reunion situations seem to constitute acoustically graded variants with distinct functions, enabling horses to increase their apparent vocal repertoire size.Electronic supplementary materialThe online version of this article (doi:10.1186/s12983-017-0193-1) contains supplementary material, which is available to authorized users.

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Mares Prefer the Voices of Highly Fertile Stallions

Cited by 17 publications

References 62 publications

An unexpected acoustic indicator of positive emotions in horses

An unexpected acoustic indicator of positive emotions in horses

Olfactory stimulation or inhibition of sexual behavior of stallions in non-breeding season

Perception of emotional valence in horse whinnies

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