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Cozzi, A., Sighieri, C., Gazzano, A., Nicol, C. J., & Baragli, P. (2010). Post-conflict friendly reunion in a permanent group of horses (Equus caballus). Behav. Process., 85(2), 185–190.
Abstract: Gregarious animals living in permanent social groups experience intra-group competition. Conflicts over resources can escalate into costly aggression and, in some conditions, non-dispersive forms of conflict resolution may be favoured. Post-conflict friendly reunions, hence reconciliation, have been described in a variety of species. The aim of this study was to explore, for the first time, the occurrence of reconciliation in a group of domestic horses (Equus caballus) and learn more about strategies used to maintain group cohesion. The behaviour of seven horses living as permanent group in an enclosure for at least 2 years was observed by video for 108 h from June to August 2007. We used a Post-Conflict/Matched Control method to assess the existence of reconciliation and third-party affiliation. Behaviours recorded Post-Conflict, or during Matched Control periods, were classified as affiliative based on previous descriptions of visual communication patterns in horses. The proportion of attracted pairs over total post-conflict situations was significantly greater than the proportion of dispersed pairs, both during dyadic interactions (p < 0.001) and during triadic interactions (p = 0.002). The results of the present study show that both dyadic reconciliation and third-party post-conflict affiliative interactions form important social mechanisms for managing post-conflict situations in horses.
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da Cruz, A. B., Hirata, S., dos Santos, M. E., & Mendonça, R. S. (2023). Show me your best side: Lateralization of social and resting behaviors in feral horses. Behav. Process., 206, 104839.
Abstract: Growing evidence shows a variety of sensorial and motor asymmetries in social and non-social interactions in various species, indicating a lateralized processing of information by the brain. Using digital video cameras on tripods and drones, this study investigated lateralization in frequency and duration of social behavior patterns, in affiliative, agonistic, and resting contexts, in a feral population of horses (Equus ferus caballus) in Northern Portugal, consisting of 37 individuals organized in eight harem groups. Affiliative interactions (including grooming) were more often performed, and lasted longer, when recipients were positioned to the right side. In recumbent resting (animals lying down) episodes on the left side lasted longer. Our results of an affiliative behavior having a right side tendency, provide partial support to the valence-specific hypothesis of Ahern and Schwartz (1979) – left hemisphere dominance for positive affect, affiliative behaviors. Longer recumbent resting episodes on the left side may be due to synchronization. However, in both instances it is discussed how lateralization may be context dependent. Investigating the position asymmetries of social behaviors in feral equids will contribute to a better understanding of differential lateralization and hemispheric specialization from the ecological and evolutionary perspectives.
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da Cruz, A. B., Hirata, S., dos Santos, M. E., & Mendonça, R. S. (2023). Show me your best side: Lateralization of social and resting behaviors in feral horses. Behav. Process., 206, 104839.
Abstract: Growing evidence shows a variety of sensorial and motor asymmetries in social and non-social interactions in various species, indicating a lateralized processing of information by the brain. Using digital video cameras on tripods and drones, this study investigated lateralization in frequency and duration of social behavior patterns, in affiliative, agonistic, and resting contexts, in a feral population of horses (Equus ferus caballus) in Northern Portugal, consisting of 37 individuals organized in eight harem groups. Affiliative interactions (including grooming) were more often performed, and lasted longer, when recipients were positioned to the right side. In recumbent resting (animals lying down) episodes on the left side lasted longer. Our results of an affiliative behavior having a right side tendency, provide partial support to the valence-specific hypothesis of Ahern and Schwartz (1979) – left hemisphere dominance for positive affect, affiliative behaviors. Longer recumbent resting episodes on the left side may be due to synchronization. However, in both instances it is discussed how lateralization may be context dependent. Investigating the position asymmetries of social behaviors in feral equids will contribute to a better understanding of differential lateralization and hemispheric specialization from the ecological and evolutionary perspectives.
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Wittemyer, G., & Getz, W. M. (2006). A likely ranking interpolation for resolving dominance orders in systems with unknown relationships. Behaviour, 143(7), 909–930.
Abstract: n many animal systems agonistic interactions may be rare or not overt, particularly where such interactions are costly or of high risk as is common for large mammals. We present a technique developed specifically for resolving an optimized dominance order of individuals in systems with transitive (i.e. linear) dominance relationships, but where not all relationships are known. Our method augments the widely used I&SI method (de Vries, 1998) with an interpolation function for resolving the relative ranks of individuals with unknown relationships. Our method offers several advantages over other dominance methods by enabling the incorporation of any proportion of unknown relationships, resolving a unique solution to any dominance matrix, and calculating cardinal dominance strengths for each individual. As such, this method enables novel insight into difficult to study behavioural systems.
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Bourjade, M., Moulinot, M., Henry, S., & Richard-Yris, M. - A. H. M. (2008). Could Adults be Used to Improve Social Skills of Young Horses, Equus caballus? Ethology, 50(4), 408–417.
Abstract: We investigated the effects of the introduction of foreign adults on the behavior of young horses. First, we observed the behavior of 1- and 2-year-old domestic horses housed in same-age and same-sex groups (a standard housing system, but different from a natural situation). Then, two same-sex adults were introduced into each experimental group. Observations made before, during and after an introduction indicated that young horses reared in homogeneous groups of young had different behaviors compared to other domestic horses reared under more socially natural conditions. After the introduction of adults, young horses expressed new behaviors, preferential social associations emerged, positive social behavior increased and agonistic interactions decreased. These results have important implications both for understanding the influence that adults may have on the behavior of young horses, and in terms of husbandry, indicating the importance of keeping young horses with adults, although further studies are still necessary. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 408-417, 2008.
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Wolff, A., & Hausberger, M. (1994). Behaviour of foals before weaning may have some genetic basis. Ethology, 96(1), 1–10.
Abstract: In this preliminary study on foal behaviour, 13 French saddlebred foals (2-3 mo old) and their dams were observed on pasture. The most important findings are the interindividual quantitative differences in foal behaviour patterns as well as in the amount of mainly foal-initiated time spent at given distances from their mares. Interindividual differences seem in part due to a sire effect
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Heitor, F., & Vicente, L. (2010). Dominance relationships and patterns of aggression in a bachelor group of Sorraia horses (Equus caballus). J. Ethol., 28(1), 35–44.
Abstract: Abstract The influence of individual factors on dominance rank and the relationship between rank distance and patterns of aggression predicted by models of evolutionarily stable strategies (ESS) of animal conflict were investigated in a managed bachelor group of Sorraia horses, Equus caballus. The group was composed of four to six stallions 3- to 12-years-old during the study period. The dominance hierarchy was significantly linear and rank was not related to age, weight, height or aggressiveness. Frequency and intensity of agonistic interactions were low, but higher-ranking stallions did not receive lower aggressiveness than lower-ranking stallions. There was some evidence that dominance relationships were more contested among close-ranking stallions, as predicted. Agonistic-related interactions among close-ranking stallions served similar functions to those among distant-ranking stallions, but the latter interacted more frequently than expected for access to resting sites and/or resting partners. Therefore, we found some evidence that agonistic-related interactions among distant-ranking stallions play a larger role in providing access to valuable and defendable resources than those among close-ranking stallions. Nevertheless, the fact that space to escape from aggression was limited and breeding access was independent from dominance rank may have reduced the benefits relative to costs of aggression and therefore limited the occurrence of contests over dominance and resources.
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Robitaille, J., Brouillette, C., Lemieux, S., Perusse, L., Gaudet, D., & Vohl, M. C. (2004). Plasma concentrations of apolipoprotein B are modulated by a gene-diet interaction effect between the LFABP T94A polymorphism and dietary fat intake in French-Canadian men. Mol Genet Metabol, 82(4), 296–303.
Abstract: Hyperapobetalipoproteinemia is a common feature of the metabolic syndrome and could result from the interaction between genetic and dietary factors. The objective of this study was to verify whether dietary fat intake interacts with the T94A polymorphism of the liver fatty acid-binding protein (LFABP) gene to modulate plasma apolipoprotein (apo) B levels. Dietary fat and saturated fat intakes were obtained by a dietitian-administered food frequency questionnaire and the LFABP T94A genotype was determined by a PCR-RFLP based method in 623 French-Canadian men recruited through the Chicoutimi Lipid Clinic (279 T94/T94, 285 T94/A94, and 59 A94/A94). The LFABP T94A polymorphism was not associated with plasma apo B levels when fat intake was not taken into consideration. However, in a model including the polymorphism, fat intake expressed as a percentage of total energy intake, the interaction term and covariates, the variance in apo B concentrations was partly explained by the LFABP T94A polymorphism (5.24%, p=0.01) and by the LFABP T94A * fat interaction (6.25%, p=0.005). Results were similar when saturated fat replaced fat intake in the model (4.49%, p=0.02 for LFABP T94A and 6.43%, p=0.004 for the interaction). Moreover, in men consuming more than 30% of energy from fat, the odds ratio for having plasma apo B levels above 1.04 g/L for A94 carriers was of 0.40 (p=0.02) compared to T94/T94 homozygotes. Results were similar for carriers of the A94 allele consuming more than 10% of energy from saturated fat (OR: 0.32, p=0.005). In conclusion, T94/T94 exhibit higher apo B levels whereas carriers of the A94 allele seem to be protected against high apo B levels when consuming a high fat and saturated fat diet. These findings reinforce the importance to take into account gene-diet interactions in the prevention and management of the metabolic syndrome.
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Krueger, K., & Farmer, K. (2011). Laterality in the Horse [Lateralität beim Pferd ]. mup, 4, 160–167.
Abstract: Horses are one-sided, not only on a motor level, but they also prefer to use one eye, ear or nostril over the other under particular circumstances. Horses usually prefer using the left eye to observe novel objects and humans. This preference is more marked in emotional situations and when confronted with unknown persons. Thus the horse’s visual laterality provides a good option for assessing its mental state during training or in human-horse interactions. A strong preference for the left eye may signal that a horse cannot deal with certain training situations or is emotionally affected by a particular person.
Pferde benutzen für die Begutachtung von Objekten und Menschen bevorzugt eine bestimmte Nüster, ein Ohr oder ein Auge. So betrachten die meisten Pferde Objekte und Menschen mit dem linken Auge. Die Lateralitätsforschung erklärt diese sensorische Lateralität mit der Verarbeitung von Informationen unterschiedlicher Qualität in verschiedenen Gehirnhälften und zeigt auf, dass positive und negative emotionale Informationen sowie soziale Sachverhalte mit dem linken Auge aufgenommen und vorwiegend an die rechte Gehirnhälfte weitergegeben werden. In diesem Zusammenhang ermöglicht die visuelle Lateralität, den Gemütszustand des Pferdes im Training und im therapeutischen Fördereinsatz zu erkennen und zu berücksichtigen.
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König von Borstel, U., Euent, S., Graf, P., König, S., & Gauly, M. (2011). Equine behaviour and heart rate in temperament tests with or without rider or handler. Physiol. Behav., 104(3), 454–463.
Abstract: The aim of the present study was to compare horses' heart rate (HR), heart rate variability (RMSSD, pNN50) and behaviour in the same temperament test when being ridden, led, and released free. Behavioural measurements included scores and linear measurements for reactivity (R), activity (A), time to calm down (T) and emotionality (E), recorded during the approach (1) and/or during confrontation with the stimulus (2). Sixty-five horses were each confronted 3 times (1 ridden, 1 led, 1 free running in balanced order) with 3 novel and/or sudden stimuli. Mixed model analysis indicated that leading resulted in the lowest (P < 0.05 throughout) reactions as measured by A1, A2, E1, E2, R2, and pNN50 while riding produced the strongest (A1, T2, HR, RMSSD, pNN50) or medium (E1, E2, R2) reactions. Free running resulted either in the strongest (A2, E1, E2, R2) or in the lowest (A1, T2, HR, RMSSD, pNN50) reactions. The repeatability across tests for HR (0.57), but not for RMSSD (0.23) or pNN50 (0.25) was higher than for any behavioural measurement: the latter ranged from values below 0.10 (A1, A2, T2) to values between 0.30 and 0.45 (E1, E2, R2). Overall, the results show that a rider or handler influences, but not completely masks, the horses' intrinsic behaviour in a temperament test, and this influence appeared to be stronger on behavioural variables and heart rate variability than on the horses' heart rates. Taking both practical considerations and repeatabilities into account, reactivity appears to be the most valuable parameter. Emotionality and heart rate can also yield valid results reflecting additional dimensions of temperament although their practical relevance may be less obvious. If a combination of observed variables is chosen with care, a valid assessment of a horse's temperament may be possible in all types of tests. However, in practice, tests that resemble the practical circumstances most closely, i.e. testing riding horses under a rider, should be chosen.
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