The eye of the domesticated sheep with implications for vision

Piggins, David; Phillips, Clive J. C.

doi:10.1017/s1357729800014612

Cited by 35 publications

(31 citation statements)

References 21 publications

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“…Sheep are basically diurnal, but they are active from dawn to evening and graze even at nighttime (Dwyer,2008). Sheep's large eyes, sizable retinal image, and tapetum improve mesopic vision, allowing sheep to avoid predators and to graze safely at dawn, dusk, and night (Piggins and Phillips,1996). Thus, sheep are an arrhythmic and crepuscular species, and the PND of sheep eyes was assumed to be 57% of the axial length in adult sheep.…”

Section: Methodsmentioning

confidence: 99%

Topography of ganglion cells and photoreceptors in the sheep retina

Shinozaki

Hosaka

Imagawa

et al. 2010

J of Comparative Neurology

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Retinal topographies of some cell types and distribution of the tapetum lucidum in the sheep's eye were investigated in this study. The tapetum was observed macroscopically in the fundus. The topographical distributions of retinal ganglion cells (RGCs), cones, and rods were simultaneously analyzed in retinal whole mounts stained with cresyl violet. Short-wavelength-sensitive (S) cones were immunocytochemically identified in retinal whole mounts. The tapetum was located dorsal to the optic disc, with the nasal part elongated horizontally and the temporal part expanded dorsally. RGCs were distributed densely in the area centralis, horizontal visual streak, and anakatabatic area. The highest density in the area centralis was approximately 18,000 RGCs/mm(2). Cones showed high density in the horizontal area crossing the optic disc and dorsotemporal area, whereas rods showed high density in the horizontal area, which was greater in height than the horizontal area of high cone density. S cones showed high density in the dorsotemporal retina. The rod/cone ratios were high horizontally in the dorsal retina to the optic disc, with a mean value of 11:1. The cone/RGC and rod/RGC ratios were lower in the horizontal and dorsotemporal retina, and the rod/cone/RGC ratio was lowest in the area centralis (9:1:1). The retinal topographies and distribution of the tapetum were specialized in the horizontal and dorsotemporal fundus. This suggests that sheep have better visual acuity in horizontal and anteroinferior visual fields and that this specialization is related to the visual ecology of sheep.

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Section: Methodsmentioning

confidence: 99%

Topography of ganglion cells and photoreceptors in the sheep retina

Shinozaki

Hosaka

Imagawa

et al. 2010

J of Comparative Neurology

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“…Based on direct observations, we noted for each of the seven stimulus sequences per valence whether the sheep had their head turned to the screen, that is, the axis of their head deviated at most 90 degrees from the head to screen axis (head parallel to the screen), for at least 2 seconds ('being attentive'). This is a conservative estimate of the sheep's attention because their visual angle is up to 313 degrees [34] and our measure may therefore reflect rather an active interest than pure exposure only.…”

Section: Behavioural Measurements: Restlessness Behaviour and Attentimentioning

confidence: 99%

Housing conditions influence cortical and behavioural reactions of sheep in response to videos showing social interactions of different valence

Vögeli¹,

Wolf²,

Wechsler

et al. 2015

Behavioural Brain Research

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Mood, as a long-term affective state, is thought to modulate short-term emotional reactions in animals, but the details of this interplay have hardly been investigated experimentally. Apart from a basic interest in this affective system, mood is likely to have an important impact on animal welfare, as bad mood may taint all emotional experience. In the present study about mood -emotion interaction, 29 sheep were kept under predictable, stimulus-rich or unpredictable, stimulus-poor housing conditions, to induce different mood states. In an experiment, the animals were confronted with video sequences of social interactions of conspecifics showing agonistic interactions, ruminating or tolerantly co-feeding as stimuli of different valences. Emotional reactions were assessed by measuring frontal brain activity using functional near-infrared spectroscopy and by recording behavioral reactions. Attentiveness of the sheep decreased from videos showing agonistic interactions toruminating sheep to those displaying co-feeding sheep. Seeing agonistic interactions was also associated with a deactivation of the frontal cortex, specifically in animals living under predictable, stimulus-rich housing conditions. These sheep generally showed less attentiveness and locomotor activity and they had their ears in a forward position less often and in a backward position more often than the sheep from the unpredictable, stimulus-poor conditions. Housing conditions influenced how the sheep behaved, which can either be thought to be mediated by mood or by the animals' previous experience with stimulusrichness in their housing conditions. Frontal cortical activity may not depend on valence only, but also on the perceptual channel through which the stimuli were perceived.

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“…Again however, as with the peripheral visual field, it is possible that for the sheep their visual acuity even in the frontal eye field may be better for moving rather than static objects (Backhaus 1959;. The large eye ball and well developed tapetum, which acts to increase retinal sensitivity by reflecting light back through the photoreceptor layer (Ollivier et al 2004), also means that sheep are likely to have good vision even at low light intensities (Piggins and Phillips 1996).…”

Section: Sheep Visionmentioning

confidence: 99%

Sheep Senses, Social Cognition and Capacity for Consciousness

Kendrick

2008

Animal Welfare

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Sheep are generally held in low regard as far as cognition and social skills are concerned. However, there is now increasing evidence from studies of their behaviour and brain function that they have highly sophisticated social and emotional recognition skills using faces, voices and smells. They are able to recognize and remember many different sheep and humans for several years or more and appear to have some capacity for forming mental images of the faces of absent individuals. The presence of such social cognition abilities in this species means that we must pay careful attention to welfare factors such as the composition and stability of their social environment as well as the nature of our own interactions with them.

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The eye of the domesticated sheep with implications for vision

Cited by 35 publications

References 21 publications

Topography of ganglion cells and photoreceptors in the sheep retina

Topography of ganglion cells and photoreceptors in the sheep retina

Housing conditions influence cortical and behavioural reactions of sheep in response to videos showing social interactions of different valence

Sheep Senses, Social Cognition and Capacity for Consciousness

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