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Author (up) Bourjade, M.; de Boyer des Roches, A.; Hausberger, M. url  doi
openurl 
  Title Adult-Young Ratio, a Major Factor Regulating Social Behaviour of Young: A Horse Study Type Journal Article
  Year 2009 Publication PLoS ONE Abbreviated Journal PLoS ONE  
  Volume 4 Issue 3 Pages e4888  
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  Abstract <sec> <title>Background</title> <p>Adults play an important role in regulating the social behaviour of young individuals. However, a few pioneer studies suggest that, more than the mere presence of adults, their proportions in social groups affect the social development of young. Here, we hypothesized that aggression rates and social cohesion were correlated to adult-young ratios. Our biological model was naturally-formed groups of Przewalski horses, <italic>Equus f. przewalskii</italic>, varying in composition.</p> </sec><sec> <title>Methodology/Principal Findings</title> <p>We investigated the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses belonging to five families with adult-young ratios (AYR) ranging from 0.67 to 1.33. We found striking variations of aggression rates and spatial relationships related to the adult-young ratio: the lower this ratio, the more the young were aggressive, the more young and adults segregated and the tighter the young bonded to other young.</p> </sec><sec> <title>Conclusion/Significance</title> <p>This is the first study demonstrating a correlation between adult-young ratios and aggression rates and social cohesion of young individuals in a naturalistic setting. The increase of aggression and the emergence of social segregation in groups with lower proportions of adults could reflect a related decrease of the influence of adults as regulators of the behaviour of young. This social regulation has both theoretical and practical implications for understanding the modalities of the influence of adults during ontogeny and for recommending optimal settings, as for instance, for schooling or animal group management.</p> </sec>  
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  Publisher Public Library of Science Place of Publication Editor  
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  Call Number Equine Behaviour @ team @ Serial 5334  
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Author (up) de Boyer des Roches, A.; Durier, V.; Richard-Yris, M.-A.; Blois-Heulin, C.; Ezzaouïa, M.; Hausberger, M.; Henry, S. url  doi
openurl 
  Title Differential outcomes of unilateral interferences at birth Type Journal Article
  Year 2011 Publication Biology Letters Abbreviated Journal  
  Volume 7 Issue 2 Pages 177-180  
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  Abstract Behavioural modifications, including modifications of emotional reactivity, can occur following early experience such as handling (manual rubbing). Here, we investigated the effects of unilateral tactile stimulation at an early stage on emotional reactions later on. We handled newborn foals intensively on one side of their body. This early unilateral tactile experience had medium-term effects: the reactions of foals to a human approach, when they were 10 days old, differed according to the side stimulated at birth. Fewer right-handled foals accepted contact with humans, they delayed first contact longer and they evaded approaching humans sooner than did non-handled and left-handled foals. These results raise questions concerning the organization of neonatal care in animals and humans.  
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  Notes 10.1098/rsbl.2010.0979 Approved no  
  Call Number Equine Behaviour @ team @ Serial 5414  
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Author (up) De Boyer Des Roches, A.; Richard-Yris, M.-A.; Henry, S.; Ezzaouia, M.; Hausberger, M. url  doi
openurl 
  Title Laterality and emotions: visual laterality in the domestic horse (Equus caballus) differs with objects' emotional value Type Journal Article
  Year 2008 Publication Physiology & Behavior Abbreviated Journal Physiol. Behav.  
  Volume 94 Issue 3 Pages 487-490  
  Keywords Animals; Animals, Newborn; Behavior, Animal/physiology; Dominance, Ocular/*physiology; *Emotions; Exploratory Behavior/physiology; Female; Horses/*physiology; Olfactory Pathways/physiology; Pattern Recognition, Visual/*physiology; Photic Stimulation; Pregnancy; Statistics, Nonparametric; Visual Fields/physiology  
  Abstract Lateralization of emotions has received great attention in the last decades, both in humans and animals, but little interest has been given to side bias in perceptual processing. Here, we investigated the influence of the emotional valence of stimuli on visual and olfactory explorations by horses, a large mammalian species with two large monocular visual fields and almost complete decussation of optic fibres. We confronted 38 Arab mares to three objects with either a positive, negative or neutral emotional valence (novel object). The results revealed a gradient of exploration of the 3 objects according to their emotional value and a clear asymmetry in visual exploration. When exploring the novel object, mares used preferentially their right eyes, while they showed a slight tendency to use their left eyes for the negative object. No asymmetry was evidenced for the object with the positive valence. A trend for an asymmetry in olfactory investigation was also observed. Our data confirm the role of the left hemisphere in assessing novelty in horses like in many vertebrate species and the possible role of the right hemisphere in processing negative emotional responses. Our findings also suggest the importance of both hemispheres in the processing positive emotions. This study is, to our knowledge, the first to demonstrate clearly that the emotional valence of a stimulus induces a specific visual lateralization pattern.  
  Address UMR CNRS 6552 Ethologie-Evolution-Ecologie, Universite de Rennes 1, Avenue du General Leclerc, Campus de Beaulieu, F-35042 Rennes Cedex, France. a.de-boyer@wanadoo.fr  
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  Language English Summary Language Original Title  
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  ISSN 0031-9384 ISBN Medium  
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  Notes PMID:18455205 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4762  
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